The Gecko Gauge SA90376 gauges and supports LP siding for one-person installation with nearly no layout time. This gauge is for use with 7/16 in thick LP siding products. It is adjustable at 1/4 in increments for 4 to 8 in siding reveals, the friction-cam mechanism supports full 16 ft LP siding lengths. It won't scratch or mar pre-painted siding.