Grom won't trip. Grom won't slip. The Grom Rover sandal has a water-friendly synthetic nubuck upper, a padded soft jersey liner, and a super soft Swellular cushion footbed for Instant Comfort. Most importantly, these boys sandals have a Reef rubber outsole with Design Detailing for traction. Less falls and skinned knees equal more fun for you and for them. Only sizes 3/4, 5/6, 7/8 and 9/10 come with a removable synthetic backstrap.