WOW!! These hooks are to BEAUTIFUL to describe! The picture does not do it justice. There is no need to buy a D Ring to use with this attachment as the D Ring is also part of the hardware. On one of the D Rings there is a squeeze connector that reminds me of a clothespin. You squeeze it open, and place the other D Ring into the connector attachment for a secure hold. What a great 2 in 1 piece of hardware! They are sold as a set of 2 of the same finish. The inside diameter for your strap is a perfect 1 1/2″, making the Butterfly total width 2 1/4″. Be sure to check out her little Sister the 1″ Butterfly Connector.