Small Point seals for Sheaffer Snorkels (to fit inside nib/section assembly, sealing around the extending filler tube) and made of long-lasting ethylene-propylene. Ethylene-propylene seals should last at least twice as long as those made of ordinary rubber, which are vulnerable to oxidization, and especially the effects of ozone. Use only with pure silicone grease, keep away from petroleum-based lubricants which you shouldn't use in the first place!