The Biosystem X4 is a comb binding machine with a punching capacity of 20 sheets (A4 70gsm) and a binding capacity of 500 sheets/51mm comb ring. It punches up to 21 holes and has an adjustable side margin and 21 push-pull pins. The machine is designed for A4 size documents and has a lifetime cutter warranty. 

Here's a more detailed breakdown: 

• Punching and Binding Capacity: The X4 can punch 20 sheets of A4 paper at a time and bind a stack of up to 500 sheets using a 51mm comb ring.
• Hole Punch: It can punch up to 21 holes, making it suitable for A4 size documents.
• Adjustable Features: The machine features an adjustable side margin to ensure proper alignment when punching and binding. It also has adjustable 21 push-pull pins for easy binding.
• Dimensions and Weight: The X4 measures 400 x 320 x 200mm (WxHxD) and weighs 9.8kg.
• Warranty: The X4 comes with a lifetime warranty on the cutter.