These cloning cylinders facilitate the isolation of individual cell clones, each generated from a single cell, yielding a homogenous population of cells. To isolate a clone, a thin layer of grease is applied to the bottom edge of the cylinder and then inverted over the clone of choice. After adding a small volume of Trypsin or EDTA, the dish is incubated at 37°C briefly until cells detach. Cells are then collected from inside the cylinder and transferred to another vessel for further growth. The cloning cylinders, molded of polystyrene, are supplied in sterile packs in three sizes. 4.7mm I.D. x 8mm high, 6.4mm I.D. x 8mm high and 9.5mm I.D. x 6.2mm high (3/16" x 5/16", 1/4" x 5/16", 3/8" x 1/4"). The cylinders are tapered so the bottom edge is wider than the top to assure a good sealing surface. The variety are packed 120 in a box, 10 of each size in a bag, 4 bags per box. Individual sizes are packed 5 per bag, 10 bags per case.