Review on 7-Piece RC Hex Driver Set - Hex Allen Screwdriver Kit with 0.9mm, 1.27mm, 1.3mm, 1.5mm, 2.0mm, 2.5mm, and 3.0mm Key Drivers - Essential Repair Tools for RC Cars, Traxxas Helicopters, and More by Tarrance Man

I only got these today to work with my RC helicopters but will write a review based on a bit of use. 1.5mm will actually fit into the hex and tighten the screw snugly. It wasn't until it was very tight, perhaps on the verge of tearing the plastic threads, that it began to slip. NONE of my other allen wrenches have done this more than once or twice and then they always slipped before being tightened - 2 or 3 full turns. 1.5mm bladed screws will work just as well. The only reason I'm giving them 4 stars overall is because I think they're too big - about 1/2 size would be perfect. BUT THEY WORK! Update: they actually work. Better than the Wiha mini set and all the other hex keys I have. I ordered a second set so I could have one for each end of the RC helicopter's tail shaft. Size wasn't an issue. 5 Stars.