Il-mudell tal-buttuna snap huwa ddeterminat mid-daqs tat-tliet biċċiet li jmiss, u l-mudelli komunement użati huma 655, 633, u 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.
It-tliet biċċiet t'isfel tal-mudell 655 jistgħu jiġu mqabbla ma 'bokkli tal-wiċċ b'dijametru ta' inqas minn 10mm;
It-tliet biċċiet t'isfel tal-mudell 633 jistgħu jiġu mqabbla ma 'bokkla tal-wiċċ b'dijametru ta' 11-15mm;
It-tliet biċċiet t'isfel tal-mudell 831 jistgħu jiġu mqabbla ma 'bokkli tal-wiċċ b'dijametru ta' aktar minn 15mm
