20 Sets Black 4040 Series Aluminum Extrusion Profile Connector Set, 20pcs Corner Bracket, 1 pcs Hex Wrench,40pcs M8 T-Nuts and M8 Hex Screw Bolt for 40S Aluminum Extrusion Profiles Rail Accessories | Includes 20pcs 3540 Corner Bracket, 40pcs M8 T-Slot Sliding Nuts & Hex Screw Bolt, 1 Wrench for 20S Aluminum Rail Accessories

The brackets and 8mm bolts were fine, but the t nuts were too wide to fit my 4040. luckily i had a bag of them from a different vendor. Seller contacted me after my first review and offered a full refund, and said they would address the issue with their supplier

I use 4040 aluminum to build a roof rack on my van. This corner bracket is very rigid. I like it.

Work well but I had to clean out the holes on some.

These work great and are much cheaper than other brackets. Though the nuts did need to be grinded down to fit in 1545 aluminum from tnutz.

These worked alright, they are made of the cheapest metal you can find and will break if enough torque is put on them.