Laskey 70DB Cornet Mouthpiece - Silver Laskey cornet rims are listed by the approximate inside diameter measurement. If a mouthpiece measures .680 on the ID, the size is the last two digits or 80 Standard throat sizes for S, P, SB and PIC cups are .144"/(#27)/3,66. Standard throat sizes for S, P, SB and PIC cups are .144"/(#27)/3,66.