Self-contained and maintenance-free gas springs from Ace Controls Inc., Farmington Hills, Mich., provide a range of forces to provide controlled motion for lids, hoods, doors, panels, and machine guards. They are available in sizes from 15 to 28 mm in diameter with forces from 10 to 2,500 N. They all have steel piston rods and cylinders, and grease chambers for low break-away forces. They work in any orientation, although mounting with the rod down is preferred. An internal valve lets the users adjust the force to an application’s requirement. When operating in hot temperatures, it is important to note that for every increase of 18°F (or 10°C), spring force increases by 3.4%.