The Nitelze Belt Clip Case fits and protects any of the Kestrel Meters but was designed with the 4000 series in mind as it has a cutout for the sensors, to continue to monitor conditions even when the user has the unit in the case. Very easy to clip it to to your belt or backpack. The case features a hook/loop closure, battery holder and front pocket. This clip case consists of a sturdy, padded, triple laminate of polyurethane, vinyl and nylon. It has a neoprene rubber inside to hold the Kestrel 4000 series snugly. The rugged clip works with up to a 2 1/4" belt, and can also be attached to your waistband. There's also a strong hook and loop strap - for secure and easy mounting to a harness strap or backpack.