Filter support collars are ideal for supporting glass funnels, crucibles, Büchner funnels, and other filtration devices. The rubber collar forms a gas-tight seal during vacuum filtration. Rubber Tapered Filter Adapter Complete Set of 8 different sizes. Size 1-8 as listed as height, top inner diameter, bottom inner diameter, and thickness. 1- 19x16x8x2.43mm 2-20x22x11x3.06mm 3-24x28x16x3.34mm 4-28x34x20x4mm 5-34x44x25x4.82mm 6-35x57x39x5.30mm 7-37x68x47x5.63mm 8-40x80x55x6mm