The Leuchtie LED Dog Collar is a totally waterproof German-engineered dog collar. This high visibility dog collar has no switches or buckles to fiddle with, simply place the LED safety collar over your dog’s head before you go out for a walk, & a unique sensor in the collar will switch it on. Once you’re back home, just take the collar off your dog & hang up. Simple! This collar is great in low-light weather conditions, enabling you to see your dog from distances.• Patented technology. You won’t find a collar like this anywhere else on the market.• 100% waterproof.• Range of sizes available.• No buckles or switches to fiddle with.• High-visibility.• Just insert ordinary AAA batteries & you & your dog are ready to use Leutchie LED Dog Collar.• Burn time approx. 100 hours. Size Guide How to measure: The Leuchtie Dog Collar is placed on your dog as a closed ring & it is only necessary to open the collar for initial activation & battery replacement. The size of your dog’s head is what you need, NOT the size of your dog’s neck. To measure simply, re-size an adjustable collar that you are able to place it over your dog’s head & pull it back off again without it being too tight & uncomfortable for your dog. Next measure the inside of the adjusted collar with a flexible tape measure as precisely as possible. Select the nearest size Leuchtie. Remember that there is only a very little amount of ‘give’ in the collar.