Tillett high specification stainless-steel, low profile washer, for low profile bolts. Special machine manufacturing technique makes this washer a premium option. The ultra-low-profile washer is to be paired with the low-profile bolts. This option reduces the bolt head presence in the seat.
This incredibly flat washer is designed to protect your race suit, your rib protector, or more importantly, your body. They enable you to tighten the seat bolts without fear of the washer pulling through, as they often do with plastic countersunk washers, or bottoming out as they can do will regular steel washers. The design of the washer also allows the head of the bolt to twist in the washer which stops the seat from breaking during the twisting forces generated by the chassis.
Care must be taken if used with a normal countersunk bolt because with regular un-modified bolts the countersink could bottom out on the seat stay on a thin seat with no spacers.