Buy a new stopper, or cut one yourself from a runner pad
Sulfuric acid, it’ll eat away the hair ( be careful)
1 3/4 in. from bottom of the bolt head to the underside of the stopper.
I have chrome the cost was between 8-9 dollars
It is chrome plated plastic. While I have not had it very long, I noted that other reviewers found it quite durable and know it came with a 5 year warranty. My previous stopper from a different company was chrome and it was terrible.
This product measures 2.37 inches deep by 2.87 inches high by 2.87 wide.