What do you think of slingshot ruler?

The slingshot ruler needs to be observed at three points and one line. When aiming at the slingshot ruler, take the left hand as an example. Hold the slingshot in your right hand, push out the slightly curved arm in parallel, stand sideways, stand in a T-shape, hold the purse in your left hand, and straighten it parallel. The left thumb is close to the left nasal tip, and some are close to the left cheek. Aiming at three points and one line, it is necessary to form a straight line on both sides of the sight to ensure that the slingshot is in a straight line and the gap is aimed at the target to be launched.