This Closing Gasket is used in many different applications, including: Manual E-61 Groupheads (three per each Grouphead) such as: Isomac, Izzo, Quickmill, Vibiemme and more Elektra Steam/Hot Water Valve EPDM or FKM 13,5 x 4 x 4mm Note: Due to the small thread size of their pins, grouphead valves often break during disassembly. We recommend disassembling your valves prior to ordering. Twist gently back and forth, back and forth, to see if they’ll loosen successfully. If not, apply just enough heat to warm the threads without melting the gaskets and try again, reapplying heat when necessary.