Old Reliables--won't touch pens without 'em
No, seriously--review SACS? They've been made the same way since 1915 and these are still around for a reason. Won't use silicone while we have these all-natural beauties. They also have not punctured, and I do tend to use DIY graphite lubes instead of talc when I rebuild. They fill quickly, adhere easily, and are in general really great parts.