50 70 the cot also comprises an outer layer comprising a butadiene acrylonitrile rubber composition said outer layer being bonded to said inner layer and having a shore a hardness of from about 70 to 85 the inner layer comprises from about 3 4 to 1 3 of the total thickness of said inner and outer layers and the outer layer comprises from about 1 4 to 2 3 of said total thickness it is well known in the art that soft cots produce superior quality yarn because greater control of the yarn fibers is possible using the relatively soft surface however soft cots tend to encourage lapping of the yarn accordingly the industry generally favors using cots having a relatively high shore a hardness rather than soft cots surprisingly we have discovered that if two ply cots are constructed having a relatively soft inner layer and a relatively hard outer layer the relatively soft inner layer allows the outer layer to deflect thus providing greater control of the yarn fibers nevertheless the relatively hard outer surface tends to diminish the likelihood of lapping as a result a very high quality yarn is obtained a typical cot constructed according to the present invention is illustrated in the figure the relatively soft inner layer 10 has a hole 11 disposed approximately centrally therethrough hole 11 being of sufficient size to receive an arbor of a spinning frame although the diameter of hole 11 may be varied depending on the arbor which is used generally arbors having diameters of 3 8 34 to 11 8 34 are encountered in the industry disposed about inner layer 10 is outer layer 12 which is bonded to inner.