Voltage: 16.5V, 3.65A ;Connector Size Internal Diameter: 5 Pin; * Note:This is for the ones made before June 2012,it is first generation; * Packing Contents: 1 x 60W Magsafe Power Adapter; 1 x Free US Plug; * Compatible Part Numbers: A1172, A1181, A1184, MA538LL/A, 661-0443, 661-4269, 661-4485, 661-4259, 661-4339 ; * Our products are all from factory direct supply, we can guarantee 100% inspection before shipping. If any problems of our products really exist, an exchange or a refund is available.