Humidity Measurement Moisture in a slab can break down the adhesives used to lay carpet or sheet goods, and it wreaks havoc with wood flooring. At $850, the HM44 Structural Humidity Measurement Set is still cheaper than redoing the floor. According to the manufacturer, the device goes beyond surface readings to provide accurate measurements of moisture content in the middle of the slab. Contact: Vaisala, 100 Commerce Way, Woburn, MA 01801; 888/824-7252; www.vaisala.com. OCTOBER JLC 1999 Products JLC' s Products by Dave Crosby Easy Patch Sooner or later, everybody cuts the hole for an electrical outlet too big. Not to worry: The self-adhesive, aluminum mesh Electrical Outlet Repair Patch is designed for a fast, easy fit around single boxes.