These are all single hole, steel, one ear support clamps. Most commonly used for EMT Conduit in the electrical sector, I find they are great for irrigation pipe, especially outdoors.

I use them for supporting Pipe, conduit, wire, and hose bibs to fences, posts, buildings etc.

The PVC ones normally sold do not stand up to the weather and usually crack or break within 2 years. 

Sizes come in 1/2" to 4".

Sizes 3" and 4" are special order and will take 7-10 days to get. They must be requested via my contact form. 3" are $6.75 each and 4" are $13.05 each.