There is an adjustment screw for tightness. You can screw it in until it is firm and stop before you crush the pipe.
I'm not sure I understand your question. Are you wanting to use this in place of unistrut or use this with unistrut? Either way, that isn't a tested and listed application for our B Vent.
This is a question best asked of The Home Depot. Amerivent makes and offers this component for use with our B Vent system and we want you to have access to it. This is especially true because we want you to properly and safely support & stabilize the pipe in your installation. However it is Home Depot that makes the call as to what they will stock. If you wish to speak with one of our Customer Service Representatives you can call them at 800-252-8467.
This extends 1 1/2" away from the wall.