The Gecko Gauge SA90338 gauges and supports 3/8 In. LP engineered wood siding for one-person installation with nearly no layout time. Working as a pair, the Gecko Gauge clamps to each siding course acting as a second set of hands to gauge and support the next course for nailing. Adjustable at 1/4 In. increments for 4 In. to 8 In. siding reveals. Will not scratch or mar pre-painted siding. Friction-cam mechanism supports full 16 Ft. LP siding lengths. Set of 2 clamps.