What is the difference between a GO Flexi-O and a GO Flexi-U?

The main difference is shape. The LITELOK GO Flexi-O’s natural shape is circular, whereas the LITELOK GO Flexi-U is formed in a more traditional U/D-Lock style. This means that Flexi-O is wearable around your waist (with a wearable kit attached) but Flexi-U is not wearable.