I have 3 Martin sprockets. 2 of them are chain size #40, and one is #41. All of them have 13 teeth, and are 7/8" wide with a 1" bore with a 1/4" keyway.
The two #40 are older, but are in good shape - just some surface rust. Set screws are missing. Martin Part #40BS13 1
The #41 is barely used, no rust. Still has original paint, minus where is wore off on the teeth. Still has the set screws. Martin Part #41BS13 1
Price is $7 each + $5 shipping
Or all three for $21 with free shipping.
The two #40 are older, but are in good shape - just some surface rust. Set screws are missing. Martin Part #40BS13 1
The #41 is barely used, no rust. Still has original paint, minus where is wore off on the teeth. Still has the set screws. Martin Part #41BS13 1
Price is $7 each + $5 shipping
Or all three for $21 with free shipping.