“The industry standard...they used to be 60 bucks, but price gouging has them up to $170 ( or more) at the supply house...even HD. Got this for 148 here...save whenever / however I can, but it's still the same old 60 dollar circ it always was.ü§†Some of the cheap import units look pretty good if you can get the flanges to match up...just not willing to experiment with other ppls systems... I'll have to try them on my own mad scientist projects first..they seem promising .”