This is a set of steel washers used in conjunction with KERDI-BOARD-ZS coarse wood screws to fasten Schluter-KERDI-BOARD to stud framing. Product Compatibility Schluter-KERDI-BOARD Building Panels Schluter-KERDI-BOARD-V Grooved Building Panels Schluter-KERDI-BOARD-E Building Panels Schluter-KERDI-BOARD-U Building Panels Schluter-KERDI-BOARD-SN Shower Niches Warning: This product can expose you to chemicals which is [are] known to the State of California to cause cancer and birth defects or other reproductive harm.