W-15A-M Water Leak Detection Monitors (4" x 4.25", pkg of 12)W-15A-M PinPoint Colormetric Paper for Water Leak Detection (4" x 4.25" adhesive back, pkg of 12 sheets to a carton). Color changes from white to green. Sensitized sheets can be cut into strips - may be placed under or around equipment to be tested for traces of water. Sensitive to 1x10 -3 std cc of water. Each sheet is individually sealed. Used to verify plumbing connections, and roof leaks. Shipyards and boat owners use these to trace leakage in cabins, and check through the hull fittings for tightness and monitor electrical boxes for in-service humidity leaks.