Re: BMS Seat
BMS has a mold(s) that they fit to your stock seat. I think they have three or four different sized molds (probably S, M, and L or something like that) and use what fits the rider. They shave the mold and seat to fit the customer. If you are a mail-in customer they shape the seat like they have been doing since Rocky (BMS) has been in business.
note: neither Mayer brother owns the rights to the original Bill Mayer seat design. I believe Russell Day-Long Seats bought/owns the original design. Rocky owns the rights to the BMS name. Rick Mayer owns his own business. All three businesses build different seats.