diff --git a/SabreTools.Models/PlayStation3/Constants.cs b/SabreTools.Models/PlayStation3/Constants.cs
index f43fa76..0344c71 100644
--- a/SabreTools.Models/PlayStation3/Constants.cs
+++ b/SabreTools.Models/PlayStation3/Constants.cs
@@ -4,6 +4,16 @@ namespace SabreTools.Models.PlayStation3
     /// <see href="https://psdevwiki.com/ps3/PS3_DISC.SFB"/> 
     public static class Constants
     {
+        /// <summary>
+        /// Identifying bytes for SFO file
+        /// </summary>
+        public const uint SFOMagic = 0x00505346;
+        
+        /// <summary>
+        /// Identifying bytes for SFB file
+        /// </summary>
+        public const uint SFBMagic = 0x2E534642;
+        
         #region Hybrid Flags
 
         /// <summary>
diff --git a/SabreTools.Models/PlayStation3/SFB.cs b/SabreTools.Models/PlayStation3/SFB.cs
index 445b1b7..da6843d 100644
--- a/SabreTools.Models/PlayStation3/SFB.cs
+++ b/SabreTools.Models/PlayStation3/SFB.cs
@@ -9,8 +9,7 @@ namespace SabreTools.Models.PlayStation3
         /// <summary>
         /// ".SFB"
         /// </summary>
-        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
-        public byte[]? Magic;
+        public uint Magic;
 
         /// <summary>
         /// File version(?)
diff --git a/SabreTools.Models/PlayStation3/SFOHeader.cs b/SabreTools.Models/PlayStation3/SFOHeader.cs
index 054111f..5b0576f 100644
--- a/SabreTools.Models/PlayStation3/SFOHeader.cs
+++ b/SabreTools.Models/PlayStation3/SFOHeader.cs
@@ -9,8 +9,7 @@ namespace SabreTools.Models.PlayStation3
         /// <summary>
         /// "\0PSF"
         /// </summary>
-        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
-        public byte[]? Magic;
+        public uint Magic;
 
         /// <summary>
         /// Version
diff --git a/SabreTools.Models/PlayStation4/AppPkgHeader.cs b/SabreTools.Models/PlayStation4/AppPkgHeader.cs
new file mode 100644
index 0000000..78a0584
--- /dev/null
+++ b/SabreTools.Models/PlayStation4/AppPkgHeader.cs
@@ -0,0 +1,236 @@
+using System.Runtime.InteropServices;
+
+namespace SabreTools.Models.PlayStation4
+{
+    /// <see href="https://www.psdevwiki.com/ps4/PKG_files"/>
+    [StructLayout(LayoutKind.Sequential)]
+    public class AppPkgHeader
+    {
+        /// <summary>
+        /// Identifying bytes for app.pkg file, "\7FCNT"
+        /// </summary>
+        public uint Magic;
+
+        /// <summary>
+        /// PKG Type
+        /// </summary>
+        public uint Type;
+
+        /// <summary>
+        /// PKG Unknown Field
+        /// </summary>
+        public uint PKGUnknown;
+
+        /// <summary>
+        /// PKG File count
+        /// </summary>
+        public uint FileCount;
+
+        /// <summary>
+        /// PKG Entry count
+        /// </summary>
+        public uint EntryCount;
+
+        /// <summary>
+        /// SC Entry count
+        /// </summary>
+        public ushort SCEntryCount;
+
+        /// <summary>
+        /// PKG Entry count (duplicated)
+        /// </summary>
+        public ushort EntryCount2;
+
+        /// <summary>
+        /// PKG File Table offset
+        /// </summary>
+        public uint TableOffset;
+
+        /// <summary>
+        /// PKG Entry data size
+        /// </summary>
+        public uint EntryDataSize;
+
+        /// <summary>
+        /// Offset of PKG Entries
+        /// </summary>
+        public ulong BodyOffset;
+
+        /// <summary>
+        /// Length of all PKG Entries
+        /// </summary>
+        public ulong BodySize;
+
+        /// <summary>
+        /// PKG Content offset
+        /// </summary>
+        public ulong ContentOffset;
+
+        /// <summary>
+        /// PKG Content size
+        /// </summary>
+        public ulong ContentSize;
+
+        /// <summary>
+        /// PKG Content ID
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 0x24)]
+        public string? ContentID;
+        
+        /// <summary>
+        /// PKG Content Padding (Zeroes)
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0xC)]
+        public byte[]? ContentZeroes;
+
+        /// <summary>
+        /// PKG DRM Type
+        /// </summary>
+        public uint DRMType;
+
+        /// <summary>
+        /// PKG Content Type
+        /// </summary>
+        public uint ContentType;
+
+        /// <summary>
+        /// PKG Content Flags
+        /// </summary>
+        public uint ContentFlags;
+
+        /// <summary>
+        /// PKG Promote Size
+        /// </summary>
+        public uint PromoteSize;
+
+        /// <summary>
+        /// PKG Version Date
+        /// </summary>
+        public uint VersionDate;
+
+        /// <summary>
+        /// PKG Content Flags
+        /// </summary>
+        public uint VersionHash;
+        
+        /// <summary>
+        /// PKG Padding Section 1
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x78)]
+        public byte[]? Zeroes1;
+        
+        /// <summary>
+        /// PKG SHA256 for Main Entry 1
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x20)]
+        public byte[]? MainEntry1SHA256;
+        
+        /// <summary>
+        /// PKG SHA256 for Main Entry 2
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x20)]
+        public byte[]? MainEntry2SHA256;
+        
+        /// <summary>
+        /// PKG SHA256 for Digest Table
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x20)]
+        public byte[]? DigestTableSHA256;
+        
+        /// <summary>
+        /// PKG SHA256 for Main Table
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x20)]
+        public byte[]? MainTableSHA256;
+        
+        /// <summary>
+        /// PKG Padding Section 2
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x280)]
+        public byte[]? Zeroes2;
+
+        /// <summary>
+        /// PFS Unknown Field
+        /// </summary>
+        public uint PFSUnknown;
+
+        /// <summary>
+        /// PFS Image Count
+        /// </summary>
+        public uint PFSImageCount;
+
+        /// <summary>
+        /// PFS Image Flags
+        /// </summary>
+        public ulong PFSImageFlags;
+
+        /// <summary>
+        /// PFS Image Offset
+        /// </summary>
+        public ulong PFSImageOffset;
+
+        /// <summary>
+        /// PFS Image Size
+        /// </summary>
+        public ulong PFSImageSize;
+
+        /// <summary>
+        /// Mount Image Offset
+        /// </summary>
+        public ulong MountImageOffset;
+
+        /// <summary>
+        /// Mount Image Size
+        /// </summary>
+        public ulong MountImageSize;
+
+        /// <summary>
+        /// PKG Size
+        /// </summary>
+        public ulong PKGSize;
+
+        /// <summary>
+        /// PKG Signed Size
+        /// </summary>
+        public uint PKGSignedSize;
+
+        /// <summary>
+        /// PKG Signed Size
+        /// </summary>
+        public uint PKGCacheSize;
+        
+        /// <summary>
+        /// SHA256 for PFS Image
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x20)]
+        public byte[]? PFSImageSHA256;
+        
+        /// <summary>
+        /// SHA256 for PFS Signed
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x20)]
+        public byte[]? PFSSignedSHA256;
+
+        /// <summary>
+        /// PFS Split Size nth 0
+        /// </summary>
+        public ulong PFSSplitSize0;
+
+        /// <summary>
+        /// PFS Split Size nth 1
+        /// </summary>
+        public ulong PFSSplitSize1;
+        
+        /// <summary>
+        /// PKG Padding Section 3
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0xB50)]
+        public byte[]? Zeroes3;
+        
+        /// <summary>
+        /// SHA256 for PKG
+        /// </summary>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x20)]
+        public byte[]? PKGSHA256;
+    }
+}
diff --git a/SabreTools.Models/PlayStation4/Constants.cs b/SabreTools.Models/PlayStation4/Constants.cs
new file mode 100644
index 0000000..fdca14d
--- /dev/null
+++ b/SabreTools.Models/PlayStation4/Constants.cs
@@ -0,0 +1,11 @@
+namespace SabreTools.Models.PlayStation4
+{
+    /// <see href="https://www.psdevwiki.com/ps4/PKG_files"/>
+    public class Constants
+    {
+        /// <summary>
+        /// Identifying bytes for app.pkg file, "\7FCNT"
+        /// </summary>
+        public const uint AppPkgMagic = 0x7F434E54;
+    }
+}