JackTight Acoustic: Acoustic Guitar Output Jack & End-Pin Repair Kit JackTight Acoustic is a revolutionary and simple-to-use tool for tightening the end-pin and output jacks of most acoustic guitars. JackTight Acoustic stabilizes and holds the output jack in place so the nut can be tightened without the jack spinning. JackTight Acoustic simply and effectively solves one of the most common maintenance issues for acoustic guitarists. Made of durable aluminum, brass and steel. Also, check out JackTight Electric: output jack repair kit for electric guitars and basses! For product video demonstration and reviews, go to JackTight.com