IF YOU PLAN ON USING A WING WITH A BUNGEE STRAP THEN YOU MUST USE THE FLEX HEAVY DUTY TO AVOID THE STRAP TWISTING These straps are between 1.8cm and 2.5cm wide. They care a snug fit on some smaller collars but are suitable for the following collars. Please see the graphic for E-Collar Technologies units this strap fits. Size guide: Small: neck circumference 26-34 cm/ 10-13”. Fits Terriers, Dachshunds, Spaniels, Medium: neck circumference 34-41 cm/ 13-16”. Fits Vizsla, Labrador, Dobermann Large: neck circumference 41+ cm/ 16”+ . Fits German Shepherd, Rottweiler Please note that if you are using a Flex Collar with a large breed, possibly using wings or long contacts with the ARC-X or 1200X then you may be better off ordering the heavy duty strap IF IN DOUBT, CALL OR EMAIL FOR ADVICE Smart No BarkYS600640C642C640C Tom Davis640X640X 2 DogARC800ARC800 CamoARC802ARC-XARC-X 2 Dog • Unpack the collar.• Unthread the free end and remove one triglide (put it aside).• You should now have: buckle + elastic section + metal triglide + webbing + 1 plastic triglide all in one long piece.• Thread the collar through the webbing until it reaches the triglide.• The collar should be touching the plastic triglide.• Take the second plastic triglide and thread it onto the webbing, so the collar sits between two plastic triglides (as shown in the video).•Thread the free end of the webbing through the chrome metal part of the buckle, threading inside-out.• This creates the first layer of the collar, with the e-collar unit sitting on it.• You should feel the strap take shape and stop moving around.• IMPORTANT: Fit it to your dog now to check size and position:• Elastic goes on the throat/underside of the neck (comfort point).• Buckle goes on one side of the neck.• Unit goes on the other side of the neck (do not place on the throat).• Collar should be tight, but you should fit two fingers underneath.• Buckle should be easy to release (if not, it’s too tight).• Collar should not wobble