The spotter arms are a great and necessary accessory for the PRX rack. I use them with the Murphy Rack and find they are useful for loading weights as well as spotting clients lifting heavy in tight quarters. Well worth the investment. They store perfectly on the hinged Murphy Rack when not in use taking up no additional floor space.
I purchased the PRX Profile Rack with Kipping Bar as well as the 4-Peg wall mount and everything is as advertised and the set up is quite simple if you follow instructions well.
I own several items from PRX and they have all been high quality. Since I don't have a reliable spotter most days (as with most garage gym owners) I decided to grab the spotter bars and they have worked as well as I expected. They fit snugly to the PRX rack and appear to be very sturdy although I have not slammed the bar down on them. I recommend to anyone looking to complete their garage gym setup.