Does anyone have these preset torque extensions?, Wondering if they make life easier. Options

[URY914]

I saw these today at my local tool store and almost bought them. Does anyone have a set or ever used them? The sales person at the store said they just started selling them. When I asked a few questions I got some stupid made up answers. If you don't know, just say so and don't give me any BS. (IMG:style_emoticons/default/mad.gif)

My question was, what happens when you reach the rated torque setting? How do they keep you from over tighting the lug nut?

"The unique design allows the length and diameter of the torque extension shaft to flex with each blow of the impact wrench once the specified torque is reached." (IMG:style_emoticons/default/WTF.gif)

What am I missing here? (IMG:style_emoticons/default/confused24.gif) Expain it to a 914 kinda guy, (IMG:style_emoticons/default/biggrin.gif)


http://bizrate.lycos.com/oid451401712.html

Product Details: 12 Piece 1/2" Drive Metric & SAE Car Wheel Torque Socket Set:Torque Extension Bars: :Torque Extensions are designed for 1/2" Dr. impact wrench rated 380-420 ft.lb.; 3/4" Dr. impact wrench rated 750 ft.lb.; 1" Dr. impact wrench rated 1,500 ft.lb.: :The various drive sizes and torque limits allow use of any impact socket with a torque extension to match the different lug nut sizes found on vehicles: :Helps prevent over-torquing of wheel nuts and can minimize wheel distortion.: :The unique design allows the length and diameter of the torque extension shaft to flex with each blow of the impact wrench once the specified torque is reached.: :Accurate to within 4%. ::Size 17, 19 & 21mm Sockets; 13/16" socket; 17-21mm: 55-135 ft/lb (75-135Nm) torque Sockets (7pcs); 13/16": 100 ft/lb (135Nm) torque Socket