Does anyone use or own any of these torque sticks by Harbor Freight? Seems like a lot of product for $49, plus ship. If so, do you use them w/shop-air settings & a 1/2" impact? Do you ever check them w/a torque wrench to see if they're somewhat accurate?

Thanks

Here's link to HF torque limiters:

http://www.harborfreight.com/12in-drive-torue-limiting-extension-bar-set-10pc-69870.html