Got to admit l broke 5 or 6 before l worked out how to use them properly .The pre drilling has got to be perfect depth and the torque set on the cordless drill got to be set perfect .Once you work that out they are excellent and countersink perfectly and strong tight bond Merbu to joists

I purchased these for a deck I was building and the quality is terrible. Despite pre-drilling and countersinking the holes I had sheared 2 out of 7 fixings. Under fairly low torque as well and it just snaps like toffee. This is a disaster as it messes up hole consistency on the board and then you have a broken fixing blocking the point where you need to put the replacement fixing. I have had similar problems with other stainless steel fixings from Zenith so instead I used their galv screws and the whole job was perfect (not a single issue out of the remaining 750 fixings I had to do). Maybe I had a bad batch but I wasn't risking it for the remainder of the job so I took them back.

Purchased January 2023; 8g x 65mm and 10g x 40mm Zenith stainless square drive decking screws. These screws are suitable for the softest pine only; garbage for anything harder. Even with pre-drilling the shank would bend and shear, or the square drive rebate would burr out. Incredibly, frustratingly poor quality - find a better brand to use.