Every question, answered.

Yes — hard, uneven steel is well inside its range. The wide flexible base bridges the gate's ribs instead of teetering across them, and the fins grip the cup by its bottom inch, so a bounce from someone sitting down doesn't rattle it loose. Knock it sideways and it settles back level.

Both. On a slick drop-in liner the wide base doesn't skate the way a bottle does, and on a corrugated or spray-in floor it bridges the ribs instead of tipping into a channel. Either way it resists tipping through the washboard-road vibration that walks loose gear around.

No. Nothing clamps to the rail, mounts to the bed, or bolts to anything — it sits on top of whatever's flat back there and picks up in a second when the tailgate goes back up.

Go by the bottom, not the rim. A base 2 to 3 inches across settles in, and the 40 oz Stanley does. Handled mugs don't — the handle lands right where a fin needs to close.

Yes — soft, shifting surfaces are exactly the kind of movement it's built to ride out. The base flexes with the mattress instead of sinking a hole into it, and settles the drink back level when someone rolls over for a blanket.

No. It never needs a magnet, so an aluminum body doesn't matter, and it doesn't depend on rail thickness or liner type either. It sits on top of whatever's flat, on a 5.5-foot bed or an 8-foot one.

That churn is the design brief. The base flexes with the vibration and brings the drink back level instead of letting it walk. It resists tipping, not everything — a direct hard kick still wins — but the ordinary jolt of a rough road is exactly the job.

Rinse it, hose it off, or run it through the dishwasher. It's one piece of flexible material with nothing to come apart, and dust, sand, or a soaking doesn't bother it.

It's called the Steadi, molded in small runs in Orange, California by Steadi Labs. Every order ships free from steadilabs.com, with 30 days to change your mind.

Some newer Ford tailgates mold in a "work surface" — a ruler, clamp pockets, a tablet slot, and a few shallow cup-shaped indentations — but those circles are a locating mark, not a holder: no walls, no grip, and the feature is limited to certain trims. The wide flexible base and fins actually grip the bottom inch of whatever's set into them, on any tailgate, molded circles or not.

No — nothing clamps or mounts, so there's no bracket to conflict with a tonneau cover's track the way a mounted cup holder can. It sits loose on whatever's flat, so when the bed's loaded with cargo or the cover rolls back, pick it up and toss it in the glovebox like anything else that isn't tied down.

Not much — a standard 12 oz can's body runs about 2.6 inches across (an industry-standard spec shared by the major can makers), already comfortably inside the 2-to-3-inch base range, and a koozie's foam still leaves it well under the fins' 3.15-inch flex ceiling. The base was never the issue in a truck bed; the ribbed tailgate and the crowned wheel well underneath it are.

Yes. The wheel well's crowned top gives a flat-bottomed cup only a sliver of contact, which is why it slides off at the first rock of the truck. The flexible base rides across the curve instead of trying to balance on top of it, and the fins hold the drink from the sides, so the crown underneath stops mattering.

One per drinker is the practical rule. Nothing clamps to a single spot on the rail or the gate, so there's no fight over one mounted holder — they ride loose in the glovebox or a door pocket until the gate drops, so keeping three or four on hand for a crew doesn't cost any rail space.

It's built for exactly that situation — a drive-in on an air mattress, reaching for a cup after dark. The fins grip by touch around the bottom inch of whatever's set into them, so it doesn't need to be lined up by sight the way balancing a cup on a mattress edge does.

It travels well as a gift because it doesn't need to match anything — no rail thickness, no bed length, no liner type, no model year. A clamp-on holder sized for one rail or a magnetic one that needs bare steel can turn out wrong for the truck it's given for; this sits on whatever's flat in any bed, short box or long.

No. Stake pockets are sized for stakes and accessory mounts — standard openings run about 1-3/4 by 2-5/8 inches, or 1-3/8 by 2 inches on the smaller convention — not for resting a drink, and the rail cap between them is too narrow for most bases anyway. The base doesn't need a pocket or a ledge; it sits on the gate, the floor, or the wheel well instead.