Over-the-shoulder restraints (often abbreviated to OTSRs) are "U"-shaped restraints which swing down from behind the rider's head to secure the torso. Some also have a belt, which secures the bottom of the restraint to the seat, passing between the rider's legs.
Most roller coasters with inversions have over-the-shoulder restraints. Over-the-shoulder restraints keep riders seated upright and secure, however they can cause discomfort if the ears and head hits restraint. This problem is aggravated by a rough ride.
From 2011, Bolliger & Mabillard have used vest harnesses instead of over-the-shoulder restraints on some of their roller coasters. Vest harnesses are thinner and more flexible than over-the-shoulder restraints, reducing headbanging.
Over-the-shoulder restraints on Arrow roller coasters used a hydraulic cylinder and various valves to secure riders. They were controlled by a foot pedal at the side of each car which is operated by the ride attendant. When the pedal is in the lock position, a one-way valve allows the restraint to be tightened but not opened, while the restraint can move freely when unlocked.