Laskey rims are listed by the approximate inside diameter measurement. If a mouthpiece measures .680 inches on the ID, the size is the last two digits or 80. Laskey describes his cups as:
D = Deep bowl like old #1. Very full sound with great control
B = Best described as a concave funnel
MD = New design. Depth between #1 and 1C.
C = Standard C cup. Good volume, brilliance and tone.
MC = First bowl moderately shallow, second deeper for tone.
S = Medium shallow. Brilliance, tone, upper register support. (Formerly known as Star.)
ES = Very shallow cup with soft entrance to throat. (Formerly known as S Star.)