The QBSTA is amazing, it is as shallow as a competitor's shallow version but handles more power and adds plenty of bass. The controls are on top which makes it easy to tune. The auto turn-on feature works perfectly with the high-level speaker inputs. We needed a 10mm bolt to attach it to the car; the manual said it should be in the box, but the unit only had an 8mm bolt that came with it. Once we got that squared away, the unit bolted down properly and the bass was coupled to the vehicle frame like it should be. Great product, but check for all the mounting hardware