Turnlock

A turnlock is a two part metal catch. One plate carrying a rotating bar sits on the bag body. Another plate carrying a slot sits on the flap. Drop the slot over the bar, turn the bar a quarter turn, and the flap stays locked down until you turn it back.

The hold is mechanical, so it does not depend on magnetic force at all. Unlike a magnet, a turnlock stays engaged whatever angle the bag ends up at, which means a bag knocked off a chair stays shut. That certainty costs speed. Closing takes two hands, a glance and about three seconds. Repeated dozens of times a day, it becomes the reason people leave the flap tucked in instead of locked.

Because the lock is both structural and the most visible metal on the bag, its finish is where age shows first. The bar rubs the plate on every single use, so thin plating wears through at that contact point. That often happens within a year or two of daily carrying. A bare patch of pale base metal on a gold lock dates a bag faster than a scuffed corner. Solid brass, whether left to age or plated thickly, holds up far better than plated zinc alloy. Turn the lock ten times before buying and watch the base plate. If the whole plate shifts, the rivets behind it are weak. A plate that works loose tears the leather it is set into.