We're going to keep this short but if you want more information you can check out the website cited at the bottom of this post.

In high school a stick check is usually performed twice per game. And, as the name suggests the officials are checking your stick to ensure it is "legal." So what are they looking at?

The crosse: There are specific measurements that must be met regarding the size of the head. We won't bore you with the details, but as long as your head is "X" spec or "U" spec you will be fine. (All heads for sale by Rocket Sports meet these requirements and therefore are legal for both high school and college play).

The pocket: When the official lifts the stick horizontally he will drop a ball in the pocket. The top of the ball must not be visible when looking directly under the sidewall. In other words the pocket should be shallow enough so that the top of the ball is covered by the sidewall and you should not be able to see the inside of the opposite sidewall.

The shooting strings: Recently, regulations were changed to ban the "U" string design pattern on lacrosse heads so ensure you have removed that configuration from your setup.

Hold: To check for "hold" hold your stick out horizontally with one hand holding on to the butt end of the stick. Drop a ball in the pocket. Slowly rotate the stick 90 degrees so the head is getting closer to the ground. The ball must fall out of the stick before the stick is vertical. If the ball stays in the pocket when the stick is vertical or even past the 90 degrees the stick has too much hold and this gives you an unfair advantage. 

All stick violations will result in a non-releasable penalty ranging from 1-3 minutes.

The head coach has the power to request a stick check on a specific player on the opposing team.

Citation: Hite, Greg. “Good, Close or Dang! How to Conduct a Stick Check.” Georgia Lacrosse Officials Association, 1 June 2019, galaxref.com/conducting-a-stick-check/