The Kastar KS4651 Lang Tools automatic slack adjuster release tool and wrench is a must-have tool for any mechanic. This tool allows you to quickly and easily release the slack on the automatic slack adjuster on most vehicles. The wrench also has a built-in ratchet for tightening the adjuster. The Kastar KS4651 Lang Tools automatic slack adjuster release tool and wrench is a must-have tool for any mechanic. This tool allows you to quickly and easily release the slack on the automatic slack adjuster on most vehicles. The wrench also has a built-in ratchet for tightening the adjuster.