     public let socket: L2CAPSocket
     
     /// Actual number of bytes for PDU ATT exchange.
-    public var maximumTransmissionUnit: Int = ATT.MTU.LowEnergy.Default {
+    public var maximumTransmissionUnit: Int {
         
-        willSet {
+        get { return buffer.count }
+        
+        set {
             
             // enforce value range
             assert(newValue >= ATT.MTU.LowEnergy.Default)
             assert(newValue <= ATT.MTU.LowEnergy.Maximum)
             
             // recreate buffer
-            
+            buffer = [UInt8](count: newValue, repeatedValue: 0)
         }
     }
+    
+    /// Whether logging is enabled.
+    public var logEnabled: Bool = false
     
     // MARK: - Private Properties
     

    
    let PDU: [UInt8]
    
    let response: () -> ()
    
    init(identifier: UInt, opcode: ATT.Opcode, PDU: [UInt8], response: () -> ()) {
        
        self.identifier = identifier
        self.opcode = opcode

        
        
    }
    
    private func log(string: String) {
        
        if self.logEnabled { print(string) }
    }
}

// MARK: - Supporting Types

public typealias ATTResponseCallback = ATTProtocolDataUnit -> ()

// MARK: - Private Supporting Types

