OEM OTK, Kosmic,FA, Exprit, Tony Kart 13mm master cylinder seal. 8mm ID, 5mm height. NOTE: 13mm seals are discontinued. Only available in a kit, 13mm PISTON WITH SEALS (BSD / SA2 / BS3-7) or 13mm PISTON WITH SEAL - BSM. BSZ Master is the replacement for BSD, BSM4 is replacement for BSM.
