The GRAV Hourglass Pocket Bubbler Rig is a 4.5-inch piece in 3mm borosilicate with a 10mm female joint, built to work as either a mini dab rig or a dry-herb bubbler. It ships with a flat-top quartz banger. It lists at $59.99 at Hemper, marked down from $68.99, and is currently sold out.
GRAV has spent two decades making the case that lab glass is the right visual language for cannabis hardware, and the Hourglass is a small, cheap, unusually complete argument for it. The name is the shape: a pinched waist between two rounded volumes, which is both the piece's whole aesthetic and the reason the water sits where it does. There is no perc, no recycler arm, no ornament. GRAV solved the problem with geometry instead of glasswork.
Four and a half inches puts this at the genuinely pocketable end of the category — smaller than most "mini" rigs, which tend to land closer to six or seven. That size normally forces a compromise: too little water, splashback into your mouth, and a piece that's unpleasant after a week. The Hourglass answers both problems directly.
It runs a deliberately low water line, so there is less water to throw around, and the mouthpiece is angled away from the chamber so anything that does move has nowhere useful to go.
Specs
- Type: Dab rig / bubbler (dual function)
- Height: 4.5 inches
- Material: 3mm borosilicate glass
- Joint: 10mm female
- Bowl capacity: Approximately a quarter gram
- Water line: Low fill by design
- Mouthpiece: Angled to reduce splashback
- Included: Flat-top quartz banger
- Price: $59.99, down from $68.99
The 3mm wall thickness is the spec that separates this from the disposable end of the market. Plenty of small glass runs thinner to hit a price, and thin glass at four inches is a piece you break moving it from a table to a shelf. Three millimetres on something this small is dense — it feels heavier in the hand than the dimensions suggest, which is exactly the signal you want from travel glass.
The 10mm joint is the honest tradeoff. Fourteen millimetres is the default in concentrates, so a 10mm piece means your existing bangers, caps and inserts probably will not fit, and your replacement options are narrower. GRAV made that call to keep the airpath proportional to the body — a 14mm joint on a 4.5-inch rig looks and behaves wrong — but it does mean you are living inside the 10mm ecosystem. The included flat-top banger softens the problem considerably, since you are not shopping for one on day one.
The dual-function claim is real and not a stretch. GRAV states it works as a mini rig or a bubbler, and the hardware supports both: swap the banger for a 10mm bowl and the same body handles flower. The quarter-gram bowl capacity tells you the intended scale — this is a piece for one person at a time, not a shared session. That is a design decision, not a limitation, and it is consistent with everything else about the thing.
It suits someone who wants filtered draws from something that fits in a jacket pocket, or who wants a second piece for travel without spending real money. It is also a legitimately good first rig — low commitment, banger included, and forgiving because there is so little to clean. It is not the piece for anyone building a primary setup, anyone already invested in 14mm accessories, or anyone who wants something to pass around.
The price is the argument. Under sixty dollars with a quartz banger in the box is aggressive for glass with GRAV's name on it, and the brand's floor is high enough that cheap GRAV still means annealed borosilicate from a company that publishes its specs. Set it against the MJ Arsenal Hydra Mini in the same bracket, or the glycerin-cooled Freeze Pipe Mini Rig at nearly double, and the Hourglass is the value pick — you are giving up cooling hardware, not build quality.
GRAV's real legacy is worth stating plainly: the brand made scientific glass normal. Before it, glass that looked like laboratory equipment read as clinical or cheap, and the aspirational tier was heady work — color, sculpture, artist names. GRAV built an entire visual identity out of clear borosilicate and clean joins, priced it for people who actually buy their own pieces, and made it obvious that restraint could be the point.
Half the glass on a modern shelf is downstream of that decision. The Hourglass, at $59.99 with a banger, is that philosophy at its most accessible.
Hemper lists this sold out with the listing live. GRAV's catalog restocks regularly, so it is worth a re-check rather than a write-off. In the meantime the GRAV Labs brand page collects the rest of the line, and the GRAV Small Wide Base Bong carries the same design language into flower.