How to Use: Stair tread gauges and shelf layout tools are easy to operate and cut to perfection. The length of the tool is easily adjustable with 4 knobs and locks securely in place to adjust to the correct angle. Specification: Item Type: Stair Treads Gauge Template Tool Material: Aluminum alloy Measuring Range: 11-60in Operation: The tool is locked firmly in place with 4 knobs, insert the stair rail between the two walls, stretch and tighten the screws firmly to measure the length and side angle, and you are ready to go Scope of Application: The stair step measurement tool can be used to cut and measure stair steps, stair risers, shelves, windowsills, closet shelves and some angle layouts Package List: 2 x Dial 2 x A16in Tie Rod 2 x B12in Tie Rod 2 x C8in Tie Rod 10 x M5 Screw 10 x M5 Knob 1 x Gasket