If you're replacing door hooks by the bag every spring, you already know they break. What most people don't know is that they break in exactly two places, for two different reasons, and both are design problems, not bad luck.
Failure one: the points snap
A hook stands up off the door wire when it's seated. It has to; that's how it catches. The problem is what happens when the pot is stacked. Every pot above pushes down on the hooks of the pot below, and a hook that stands proud takes that load on its points. Polypropylene is tough, but it is not tough enough to carry a stack of wire pots on two little tips through a winter of freeze and thaw. The points snap. You find out in March.
The fix is to let the hook lay flat under load instead of fighting it. Relief cut into the points lets the hook fold down against the wire when weight comes on, so the load passes into the pot frame and not into the plastic. That is what "FlatStack" means. It isn't a brand name, it's the feature.
Failure two: the cinch cracks
Look at the base of the cinch on a broken hook and you'll almost always find the crack starts at an inside corner. A sharp corner concentrates stress. Every time the band flexes the hook, all of that flex piles into one line at the corner. Thousands of cycles later, it lets go.
This one is a molding decision. A radiused hole at the base of the cinch spreads the flex across a curve instead of piling it onto an edge. It's a small change in the tool and it removes the crack initiation point entirely. The hook bends and comes back.
The failure that isn't a failure: the wrong span
A lot of "broken" hooks were never right for the pot. If the center-to-center span is short for the door, you're forcing the hook to seat, and you'll snap points doing it. Overall length doesn't tell you this; only the cinch-to-hook dimension does, and almost nobody publishes it. Here's how to measure your pot and what number to look for.
Material matters less than people think, until it doesn't
UV-stabilized polypropylene is the right material for this part. It flexes, it floats, it doesn't rust, and with a UV package it holds up to a season on deck in full sun. Without the UV package it chalks, gets brittle, and cracks out in a year or two regardless of design. If a hook is cheap enough to make you wonder, that's usually where the money came out.
What we did
We designed the FlatStack hook around both failures: relief at the points, a radiused cinch, full material at the bungee loop, 3-1/2" center to center for a commercial pot, heavy section, UV-stabilized PP, molded in Baltimore. Our goal is a hook that outlives the wire it's tied to.
When one breaks, and eventually one will, send us a picture. Where it broke tells us what to fix next.