Oatey 42192 Bathroom Sink and Tub Drain Strainers, 1 1/2-Inch, Cast Iron Low profile for tight spaces Designed for use on built up Shower bases of tile or marble, where a Shower pan liner is used The clamping ring locking bolts screw into brass inserts to prevent stripping Keyhole slots in the clamping ring allow it to be clamped without removing the bolts