Lab cork stand, made of compressed cork material. Durable and affordable. 80mm x 33mm (3.1"x1.3"): Suitable for 15-250mL round bottom flasks 110mm x 60mm (4.3"x2.4"): Suitable for 100-1000mL round bottom flasks 140mm x 90mm (5.5"x3.5"): Suitable for 500-2000mL round bottom flasks 160mm x 105mm (4.1"x4.1"): Suitable for 3000-20000mL round bottom flasks Size is outer diameter by inner diameter. Price is for an order of TWO cork stand units.