diff --git a/Sources/Bluetooth/Data.swift b/Sources/Bluetooth/Data.swift
new file mode 100644
index 000000000..12cf03db2
--- /dev/null
+++ b/Sources/Bluetooth/Data.swift
@@ -0,0 +1,80 @@
+//
+//  DataContainer.swift
+//  Bluetooth
+//
+//  Created by Alsey Coleman Miller on 11/4/24.
+//
+
+#if canImport(Foundation)
+import Foundation
+#endif
+
+/// Data container type.
+public protocol DataContainer: RandomAccessCollection where Self.Index == Int, Self.Element == UInt8, Self: Hashable {
+    
+    init()
+    
+    init<C: Collection> (_ collection: C) where C.Element == UInt8
+    
+    mutating func reserveCapacity(_ capacity: Int)
+    
+    subscript(index: Int) -> UInt8 { get }
+        
+    mutating func append(_ newElement: UInt8)
+    
+    mutating func append(_ pointer: UnsafePointer<UInt8>, count: Int)
+    
+    mutating func append <C: Collection> (contentsOf bytes: C) where C.Element == UInt8
+    
+    static func += (lhs: inout Self, rhs: UInt8)
+    
+    static func += <C: Collection> (lhs: inout Self, rhs: C) where C.Element == UInt8
+    
+    /// Return a new copy of the data in a specified range.
+    ///
+    /// - parameter range: The range to copy.
+    func subdata(in range: Range<Index>) -> Self
+}
+
+#if canImport(Foundation)
+extension Data: DataContainer {
+    
+    public static func += (lhs: inout Data, rhs: UInt8) {
+        lhs.append(rhs)
+    }
+}
+#endif
+
+extension LowEnergyAdvertisingData: DataContainer {
+    
+    public mutating func reserveCapacity(_ capacity: Int) {
+        // does nothing
+    }
+    
+    public func subdata(in range: Range<Int>) -> LowEnergyAdvertisingData {
+        var data = LowEnergyAdvertisingData()
+        for (newIndex, oldIndex) in range.enumerated() {
+            data[newIndex] = self[oldIndex]
+        }
+        return data
+    }
+}
+
+extension Array: DataContainer where Self.Element == UInt8 {
+    
+    public static func += (lhs: inout Array<Element>, rhs: UInt8) {
+        lhs.append(rhs)
+    }
+    
+    public mutating func append(_ pointer: UnsafePointer<UInt8>, count: Int) {
+        let newCapacity = self.count + count
+        self.reserveCapacity(newCapacity)
+        for index in 0 ..< count {
+            self.append(pointer[index])
+        }
+    }
+    
+    public func subdata(in range: Range<Int>) -> [UInt8] {
+        .init(self[range])
+    }
+}
diff --git a/Sources/Bluetooth/Extensions/DataConvertible.swift b/Sources/Bluetooth/Extensions/DataConvertible.swift
index 122a43d35..5af7a03d0 100644
--- a/Sources/Bluetooth/Extensions/DataConvertible.swift
+++ b/Sources/Bluetooth/Extensions/DataConvertible.swift
@@ -20,18 +20,24 @@ internal protocol DataConvertible {
     var dataLength: Int { get }
 }
 
-#if canImport(Foundation)
-extension Data {
+extension DataContainer {
     
     /// Initialize data with contents of value.
     init <T: DataConvertible> (_ value: T) {
         let length = value.dataLength
-        self.init(capacity: length)
+        self.init()
+        self.reserveCapacity(length)
         self += value
         assert(self.count == length)
     }
 }
-#endif
+
+extension DataContainer {
+    
+    mutating func append <T: DataConvertible> (_ value: T) {
+        self += value
+    }
+}
 
 extension BluetoothUUID: DataConvertible {
     
@@ -94,40 +100,3 @@ extension UInt32: UnsafeDataConvertible { }
 extension UInt64: UnsafeDataConvertible { }
 extension UInt128: UnsafeDataConvertible { }
 extension BluetoothAddress: UnsafeDataConvertible { }
-
-// MARK: - DataContainer
-
-/// Data container type.
-@usableFromInline
-internal protocol DataContainer: RandomAccessCollection where Self.Index == Int {
-    
-    subscript(index: Int) -> UInt8 { get }
-        
-    mutating func append(_ newElement: UInt8)
-    
-    mutating func append(_ pointer: UnsafePointer<UInt8>, count: Int)
-    
-    mutating func append <C: Collection> (contentsOf bytes: C) where C.Element == UInt8
-    
-    static func += (lhs: inout Self, rhs: UInt8)
-    static func += <C: Collection> (lhs: inout Self, rhs: C) where C.Element == UInt8
-}
-
-extension DataContainer {
-    
-    mutating func append <T: DataConvertible> (_ value: T) {
-        self += value
-    }
-}
-
-#if canImport(Foundation)
-extension Data: DataContainer {
-    
-    @usableFromInline
-    static func += (lhs: inout Data, rhs: UInt8) {
-        lhs.append(rhs)
-    }
-}
-#endif
-
-extension LowEnergyAdvertisingData: DataContainer { }
diff --git a/Sources/Bluetooth/LowEnergyAdvertisingData.swift b/Sources/Bluetooth/LowEnergyAdvertisingData.swift
index 1a3f85af5..30e905b16 100644
--- a/Sources/Bluetooth/LowEnergyAdvertisingData.swift
+++ b/Sources/Bluetooth/LowEnergyAdvertisingData.swift
@@ -76,11 +76,8 @@ public extension LowEnergyAdvertisingData {
         }
     }
     
-    init? <C: Collection> (_ collection: C) where C.Element == UInt8 {
-        
-        guard collection.count <= 31
-            else { return nil }
-        
+    init<C: Collection> (_ collection: C) where C.Element == UInt8 {
+        precondition(collection.count <= 31)
         self.init()
         self.length = UInt8(collection.count)
         collection.enumerated().forEach {