The SSL portable barrel compression fixture or bat tester was developed for the softball industry to measure the barrel stiffness of a bat. The barrel compression of a bat does show correlation to how the bat will perform. The lower the compression, the better the bat will perform.
The device is used to determine when a bat has exceeded its intended life and also reveals when bat barrels have been tampered with (i.e. when a bat has been rolled or when the bat barrel has been shaved).
The bat compression tester is completely portable and does not require power.