“It was unclear when I ordered this item what it was for but I added it to my order anyway. I was thinking it helped you hold the nozzle when you insert it. It turns out that it holds the pop-up riser in the "up" position even with the water "off" to make it easy to get at the nozzle. That's much more useful than I originally thought.”
“The collar is purely a matter of convenience. The same task could be completed with a small piece of TIG wire but the collar is easy to find and simple to use.”