This is a 2 in 1 folding rule with a big difference, having a digital read out of the angles. Measure both the angle and length at the same time with a clear display and bold markings in both Metric and Imperial on the rules. The rules are made from corrosion resitant stainless steel. The battery life is around 200 hours and is protected by auto shut down after 6 minutes. They have a clever auto-start of the digital read out, this will switch on as soon as you open the rule, saving time and fumbling for a button. A serious tool for any carpentry or setting out tasks.