This is a genuine original battery for use in the Zoll AED Pro, part number 8000-0860-01.
 
Zoll AED Pro Battery 8000-0860-01 Original Medical battery
Zoll Battery Part Number: 8000-0860-01
Voltage / Capacity: 12 Volt 4.2 Ah
Dimensions: 168mm (L) x 75mm (W) x 45mm (H)
Approx. Weight: 385g
Chemistry: Lithium Primary