They’re stamped with 3/8 G70. The spring is pretty much the only thing that can be made cheaply, which these are. If you need hooks for personal use, get these. If the hooks are for public or rental use, they’ll only last a few uses because the safety spring metal is thin and the spring itself only winds once around the latch; it’s just not a heavy duty safety latch.Works perfect on our wreckers.Overall these are good hooks, BUT the cotter pins are flimsy.One was crushed in the package and fell out before use.I replaced the cotter pins.They have a pin so can be added to chains and loops of cable.Good hook at a reasonable price.Horrible hooks. I used them to chain down my bobcat using normal 5400 lbs ratchet binders and 2 broke on my first trip using them. My G40 blue hooks are stronger. Very unsafe and dangerous for transportnice and heavy with strong clips