The D4 portable bluetooth speaker was designed to be used on the go with its small size, light weight, and carrying strap. It is fully wireless, and its battery life can reach 12 hours at medium volume and it only weight 500 grams. The SuperTooth D4 is the perfect lightweight outdoor speaker. The D4 also has the convenience of NFC technology for instant pairing to a compatible mobile device. Users simply touch the SuperTooth D4 against their phone in order for the devices to recognise each other.