the rubber is to make a diafram for a drop valve and to Carrie in the van,, should i come across any thing unusual,,, story is i visited a customer who told me thay had a very old toilet 30 years old, and it worked by pulling a button on top,,, i thought thay were mistaken as ive never come across a drop valve more than say 15 years max... how ever on the visit thay told me it was italy and was 30 years old,, all it needs is a simple gasket but i cant id the drop valve so i cant get one,,, even if thay were avalable,, tried all mine in the van and non match ... its simler to say a 1 1/4 whb washer,,, as any one come across an older drop valve???