📦 GRK Caliburn XL HandyPak Package CAL1964312HPXL Review

The absolute best fastener for concrete. Easy installation and high holding capacity. I attached the 4x4 struts with these bolts and WOW! worth $$$

I find that these screws break if the holes are not drilled deep enough, or for some reason there is a lot of dirt in the concrete when the screws are inserted. Usually the head will loosen if the hole fills up (or doesn't get deep enough. Also, the metal of the screw is brittle, don't bend it (offset of the holes between the concrete and the fastened material) or it will break. But with the due care, the screws work.

They might work in fairly fresh concrete, but they don't fit my fifty-year-old porch. I drilled the pilot holes with the included drill (well, a few holes - the drill wore out after six holes so I had to buy a few more) to a depth of well over an extra 1/2 inch. clarified, blown out the dust and tried to drive the screws. No it does not. You walk half to two-thirds of the way and stop. At this point they will not give in. I've tried unscrewing them, re-drilling the hole with a hammer drill and…