Closure Only, GPI 13-425, Red, Open Hole, Polypropylene. Used with Viton O-Rings and threaded outer joints for making grease-free, vacuum tight seals on 14/10 MINUM-WARE glassware components. The 8-425 size is used on the sidearm of Hickman still head and MW-81 GC collection vial, while the 13-425 is used on the MW-56 two neck flask sidearm.