Hi Guyon,
I bought one a year ago, only to replace it with a Sinclair rest. The Benchmark proved to be useless for use with AR style rifles because that monster knob on the base interferes with the mag extension and the rear of the rest is impossible to get a good hold of the buttstock because of the sling swivel in the buttstock.
The bag you see used on the front of the rest is cheap plastic and is glued on. It was pretty useless so I replaced it with a small owl ear bag from Protektor.
It is adequate for use with my conventional rifles. Still, there is no comparison to a good Sinclair or Hart rifle rest. Of course, the Sinclair and Hart rests are about 2.5 times the cost, too.
Honestly, I don't think the Benchmark is worth what it costs at all. Two or three Protektor sandbags would do you just as well.