Rubber base gasket for the earlytype L581 Rear Light and this works in conjunction with the base gasket part No 576401 Will also fit the later type L581 rear light if you do not have the later type combined shroud/gasket, the difference is the shroud/gasket as the lampholder is the same  This item was manufactured on Tooling commisioned by the Isetta Owners club ensuring once again even small parts become available