Jonard's WTL-12 is designed specifically for cutting out single and double gang old work boxes, this wall template level is perfect for ensuring the boxes are level every time.
The WTL-12 is easy to use. Simply locate where you wish to install your wallbox. Place the WTL-12 against the wall and use the level to insure the box is straight. Either hold in place with one hand or the template can be screwed into place using the two holes. Trace the large rectangle for single gang boxes or trace the entire WTL012 template for double gang boxes. Remove the WTL-12 and cut the wallboard following your traced lines.