Every question, answered.

Measure the base, not the lid or the flip straw. A base 2 to 3 inches across settles in — the 40 oz Stanley fits. Under 2 inches it's too loose to grip, and the widest insulated tumblers, well past 3 inches, are too wide for the fins to close around.

That's the exact mismatch this is built for. Factory wells were molded around a 12 oz can, commonly 2.5 to 3 inches across, while today's insulated tumblers run wider. It sits across the console's opening instead of forcing the bottle into a well that's too small, and the base and fins do the gripping the well can't.

Those run wider at the base than what settles in here — some past 3.5 inches. The rule holds a floor and a ceiling both: 2 to 3 inches across is the range, so a standard-mouth bottle fits and the widest wide-mouth sizes are honestly past it.

Yes, at least as well as anywhere else. The wide base and the fins don't need softness to grip; they hold steady on concrete, gym tile, a treadmill's molded tray, or a hard desk the same way they do on a car console.

That's the specific failure this addresses. A machine's built-in ring is sized to a generic cup, and the running vibration is constant enough to walk a loose-fitting bottle toward the tray's edge over a run. This grips the base directly instead of just cradling it, so it holds steady through a run's worth of stride instead of migrating toward the edge.

That's the point of using it there. A wide base and gripping fins make a bottle less likely to go over when an elbow catches it reaching for a notebook or a charger — it resists tipping. It isn't a lid, though, so pair it with a sealed bottle if the keyboard is close enough to worry about.

No. Nothing bolts to a frame, clips to a machine, or tucks under anything. It sits on top of whatever surface is there — car console, gym floor, treadmill tray, desk — and travels with the bottle instead of staying behind.

Rinse it or run it through the dishwasher — whichever stop it's due for. It's one piece of flexible material with nothing to take apart, so gym sweat, car dust, and nightstand grime all come off the same way.

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

Not necessarily — capacity and base width aren't linked the way that sounds. A Simple Modern Trek 40 oz Tumbler tapers hard, with a base around 2.14 inches under a wider 3.12-inch rim, while Yeti holds one base diameter, about 2.75 inches, across both its 20 oz and 30 oz Ramblers. The ounce count on the label doesn't tell you the number that actually matters; measure the base itself.

No — position is what matters, and the Quencher's handle sits up near the lid, well above the base, not down where the fins need to close. That's different from a mug, whose handle sits low against the base and lands right where a fin needs to grip. A Quencher's actual base, about 3.1 inches at 40 oz, settles in the same way any other base that size does.

A 30 oz Quencher's base runs about 3.15 inches — right at the edge the fins flex to, so it seats snugly rather than easily. A 24 oz Owala FreeSip is close behind at about 3.12 inches and fits the same way. Owala's 32 oz FreeSip grows to about 3.43 inches at the base, which is honestly past what the fins close around.

No — the fins grip the bottle's base directly, not the surface underneath it, so condensation doesn't change the hold. Sweating bottles leaving rings on car consoles and desks is common enough that it's spawned its own category of coasters and holder inserts; this skips that problem by holding the bottle itself rather than relying on the surface it's sitting on.

It's one piece of flexible material with no separate parts — no clip, no bolt, no strap — to snap off or work loose from being thrown in a bag daily. It packs flat and travels the same way the bottle it grips does.

There's nowhere for it to trap anything — it's a single molded piece with no seams or crevices, so whatever it picks up rinses or dishwashers off the same way dust from a desk or grime from a nightstand does.

It can. A boot or sleeve is built to add roughly half an inch to a bottle's effective base, which helps a narrow bottle rattling around inside an oversized holder. Pushed onto a base already near 3.1 to 3.15 inches, though, it can widen that base past what the fins close around — worth checking the bare-base fit first.

Either works. It's built to travel — it packs flat in a bag pocket and moves with the bottle from the car to the gym to the desk. If the same bottle sits in two places at once, like a gym bottle that lives in the gym bag while a different bottle stays on the desk, a second one just means neither spot goes without.

It's not built to clamp to a stroller handlebar, so it doesn't fix a mount that's rotating on its own. What it does help with is the bottle itself once it's set down loose — on the stroller tray, at a park bench, or anywhere else along the walk with no holder built for it at all.