Model zaskočnega gumba je določen z velikostjo naslednjih treh kosov, pogosto uporabljeni modeli pa so 655, 633 in 831.
The three BCD pieces are generally referred to as "the next three pieces". The surface of the snap button (A piece) can be changed at will, but the next three pieces generally have their general rules.
Spodnje tri kose modela 655 je mogoče kombinirati s površinskimi zaponkami s premerom manj kot 10 mm;
Spodnje tri kose modela 633 je mogoče kombinirati s čelno zaponko s premerom 11-15 mm;
Spodnje tri kose modela 831 je mogoče kombinirati s površinskimi zaponkami s premerom več kot 15 mm
