Rubber plug for the rear brake drum adjustment hole. Fits aluminum drums for Datsun 240Z, 260Z and 280Z, 1970-78. There are two holes on the brake drum, one hole is about 9.5mm and the other is about 11mm. We have seen the larger 11mm hole have the lead plug. This rubber plug will fit the smaller hole tight and could work in the larger hole with a little glue or silicone.