shimano brake br-m988 master cylinder protection

2 parts:
-the washer should be printed from stiff plastic (petg, pla)
-the seal is from flexible

very snug fit, make sure you printer is dialed in

1. break away the stock plastic washer that regulates free stroke (you wont be able to remove it's pin anyway) before fitting in the new washer

2. polish out any scratches and clean internals before the assembly

3. probably you will need to cut the seal with a razor in order the plunger to make through the hole

4. make sure the hole in the seal is round, use something hot to remove any blobs

5)glue the seal onto the washer with some rubber-like glue

For a right handle - mirror both parts