We redesigned the Presta Grommet in 2012 to fit to modern standards. Our design works so well, it's been copied by others. Our design engages the Presta valve just below the cap threads and requires less insertion. The head is now very easy to get on and off. Our newest version uses Urethane Elastomer. It's softer and stronger. It lasts more than 5 times longer, gives a better seal and flexes to work anywhere along the presta shaft for better tubeless application. Safe for all types of Presta valves, including tubeless and tubeless-conversion valves. Will not harm newer lightweight performance valves. Fits all Prestaflator BIG Push/pull Presta heads. Also fits all Silca pump heads that use the 24.1 or 242 Gasket.