metal lower disc 24 having a tapered upper surface 26 and an internally threaded central opening 28 surrounded by additional openings 30 a bolt 32 is inserted through the central opening 14 of the upper disc 12 and through split ring 20 and resilient ring 22 and threadedly engages the opening 28 in the lower disc 24 preferably the resilient ring 22 is square in cross section as this permits greater frictional engagement with the walls of the drain opening in use the floor sink drain screen lock 10 is inserted into the mouth of a floor sink drain so that the tapered lower surface 18 of the upper disc 12 rests on the periphery of the floor sink drain opening the bolt 32 is then tightened which serves to draw the lower disc 24 toward the upper disc 12 which compresses the split ring 20 and resilient ring 22 causing them to expand laterally to frictionally and sealingly engage the wall of the floor sink drain opening this ensures that the drain screen lock 10 will not be displaced during use when the floor is washed water can flow through openings 16 in the upper disc 12 and openings 30 in the lower disc 24 however any large objects will be blocked by the remaining structure of the upper disc 12 if the openings 16 or 30 become clogged over time bolt 32 can be loosened allowing split ring 20 and resilient ring 22 to contract and hence allowing the drain screen lock 10 to be removed for cleaning the resilient ring 22 serves to retain the split ring 20 in position between the upper disc 12 and.