This is a buckling collar with 1/2" width and it comes with an O-ring as a point of attachment which is connected to a D-ring. Great on its own or with a leash. Simple enough to wear in public.

Small fits 10.75" - 13.75" (27.9 - 36.8cm)
Medium fits 12" - 15.25" (33 - 41.9cm)
Large fits 12.75" - 17" (34.3 - 45.7cm)

XLarge fits 14.5"- 19" (36.8 - 48.3cm)