Leather piston cup seal 1.1 inch (28 mm) diameter. Some fitting might be required. Use for BSA & Lincoln Jeffries Underlevers, Webley Mk3, Original/Diana Mod 35 &45 & 50, Haenel Pre War & 303, Anschutz 335, BSF Model 54 & 55, Crosman 3100, Anschutz 335, Luczink 87, and many others. Interior hole is 3/16 inch. Leather naturally varies in thickness, however, these seals are made to very close tolerances. They will expand a little to fit an out of round or over sized compression tube or can be reduced in diameter with sand paper and made to fit a slightly undersized compression cylinder. You might need to purchase LEA1.1A to accompany this seal.