FRT Triggers Low Shelf, High Shelf in one easy pic how it works - Both good for AZR
Jun 15th 2026
Welcome back to FRT Trigger History and Facts - Part 2 - FRT Triggers Low Shelf, High Shelf in one easy pic
Here we go with a pretty simple one folks. Once you see it it all makes sense.
Best part is the ARIZONA REGULATOR ® IS NOT Shelf dependent. We do not sit on the shelf inside the lower.
Now and then I get calls asking about Low Shelf, High Shelf, etc. So I figured Id see if I could get those all covered in one easy to see pic.
Sure enough after a couple rearangements I think I got you guys a decent view of each side by side.
Remember if you will. I am a machinist not a photographer or video guy, I do what I can with them but I'm good with the metal.
What we have here from bottom to top is:
A Low Shelf lower
This one is an old Nodak Spud A1 Clone lower. If you look inside the lower at the selector you will see the top of the selector is visible. There is no strip of material above it at the reciever wall. Tip of green line. This is due ot the Low Shelf where the Shelf terminates at the backside of the selector a bit below the top of the selector.
A High Shelf lower
This one is an old American Spirit lower. If you look inside this one you will see the shelf extends over top of the selector so it is visible thru the center recess where the tail of the trigger bar goes but not at the end by the receiver wall. This is the high shelf extending forward to the FCG pocket.
A Colt Lower which is a Low Shelf lower
This one has the web in it which if you measure down at the rear lug area you will find the Colt is a Low Shelf lower even with the web in there. We all love you Colt can we have some lowers without the web.

Speaking of rear lugs brings up another great point for yall.
I thought about those too when I engineered the ARIZONA REGULATOR®. Thus I engineered to be less in height when seated than the rear lug projects. Therfor if the rear lug can close and takedown pin goes in no matter if its High Shelf or Low Shelf there is plenty of room for an ARIZONA REGULATOR® in the lower receiver.
One other notable thing would be that I also engineered in to cover the standard AR pocket widths. As you see in the High Shelf lower the pocket is a wider opening all the way back. And when you look at the Low Shelf lower below it you will see there is a pillar that comes up from the floor of the lower and terminates at the top of the lower receiver which makes the pocket a bit narrower at that location.
Those type lowers were also taken into account along with knowing there are wide opening lowers with high shelf and low shelf then throw in the narrow opening lowers like the low shelf in the pic and you now have two more shelf slash AR pocket cuts to deal with.
Nope I took care of all of that for you. Simple as the pic. If yours is open without a web or some other obstruction you are good to go. Man thats easy.
Our ARIZONA REGULATOR® products drop right into all those different lowers. Just remember to put the Regulator into the pocket of the upper then tip the receiver closed like the instructions call for.
Till next time
R/S
J.D.