The Kids Grombows are new to 2013, they are soft and squishy. Your Grombows will love their Grombows Guaranteed! Single Layer â No Arch. These kids Grombows are soft and squishy, with a smooth, comfortable neoprene strap. The comfortable toe piece is secured with a box X stitch and is sewn with bonded nylon thread. The Rainbow logo is found on both the strap and is embossed in the top sole. The bottom is the Rainbow Non-Slip sole. For the toddlers the four smallest sizes come with a back strap attached at the heel, if you don't need it, just cut it off!