The Rogz Alpinist K2 Choker Half-Check is a great product. I use it as a substitute for a Martingale collar when to quickly slip a collar on and off a dog. The Large size is a lot WIDER than the Medium size, so size Large is better for a strong puller. The Medium size (purchased separately) worked on a calm dog with a smallish neck, our foster dog. But the Medium size does not fit our personal dog, even though she weighs the same as our foster dog. As with a lot of collars, it seems like the advertised measurements do not take into account hems, overturned fabric, and similar bindings. For example, the FUNCTIONAL maximum for the Medium-sized collar is 15.5 inches, not 16 inches. Meanwhile, the smallest size I can adjust on the Large-sized collar is 17 inches because there is a stiff label wrapping on the inside ring. So this collar might not fit dogs with neck sizes between 15.5 and 17 inches. By the way, the stiff wrapping is very useful on the OUTSIDE ring of the collar to keep the Choker from sliding open.
The Rogz alpinist choker is a great item. I bought two different colours for my Border-Collie. Extreme good quality, great colours. The website works great, and handling and delivery goes fast. ++++
Tough and practical, washes with no loss of colour, would recommend.
Excellent collar. Recommend