These versatile adapters, made from synthetic rubber, provide a functional alternative to boring holes through traditional rubber stoppers. They are designed to fit Buchner and fritted glass funnels, porcelain filters without headpieces, and for reverse flow cleaning for filter crucibles. Adapters can be used to support funnels, Gooch crucibles, filter tubes, and other apparatuses in filtration assemblies, and are functional even if not tightly fitted around the funnel stem. They can be used individually, or nested with adjacent sizes. Adapters are autoclavable. Measurements: Adapter #1: 21mm top outer diameter (OD); 10mm bottom outer diameter (OD); 17mm top inner diameter (ID); 6mm bottom inner diameter (ID) Adapter #2: 27mm top OD; 16mm bottom OD; 20mm top ID; 10mm bottom ID Adapter #3: 36mm top OD; 21mm bottom OD; 30mm top ID; 15mm bottom ID Adapter #4: 45mm top OD; 27mm bottom OD; 39mm top ID; 21mm bottom ID Adapter #5: 57mm top OD; 37mm bottom OD; 50mm top ID; 29mm bottom ID Adapter #6: 70mm top OD; 45mm bottom OD; 62mm top ID; 35mm bottom ID Adapter #7: 90mm top OD; 55mm bottom OD; 80mm top ID; 46mm bottom ID