The Reliant Data Acquisition Unit (DAU) is a rugged, portable device with no external controls that records and stores readings from the iButton checkpoints, along with the time and date of each reading. The device is protected by an enclosure of glass-reinforced polycarbonate (Lexan). Successful readings are confirmed both by audible and visible indicators. The reliant stores 5,460 readings in nonvolatile RAM. The unit will operate for one year or 500,000 readings on three “AAA” batteries, which are user-changeable. The Reliant measures 3.88″ x 1.9″ x 1.36″ and weighs 5.3oz.