ROK Zero Jar, Set of 2
Last updated: 25 October 2026
The ROK Zero Jar is a glass coffee jar with a plunger lid. You push the lid down onto the beans to squeeze the air out, and an O-ring seals it, so oxygen does not get at your coffee. Each jar holds 600ml, enough for a 250g bag. On 25 October 2026 ROK sold a pair for £49, in stock.
What the ROK Zero Jar is
ROK is a London company known for its GC manual espresso maker, which works without electricity. The Zero Jar comes from the same idea: a simple mechanism instead of a valve or a pump.
Instead of a lid with a one-way valve, the Zero Jar has a plunger. So you press it down until it meets the coffee, and the air goes out past the seal with a hiss. To open it, you pull the handle up and the rolling O-ring lets the plunger rise.
What it does
- Pushes the air out: the plunger sits right on top of the beans, so there is little air left in the jar to stale them.
- Seals without a valve: there is no switch or valve to set, just the O-ring.
- Comes as a pair: two jars in the box, so you can keep two coffees on the go, or coffee and something else.
- Stores other dry food: ROK says it works for any granular food that suffers from oxygen damage, not just coffee.
Key facts
- Price: £49 for two at ROK and at Buy Me Once
- Capacity: 600ml per jar, sized for a 250g bag of beans or ground coffee
- Size: 10cm across and 11cm high, according to Buy Me Once
- Materials: thick-walled glass, a soft silicone base and a glass composite plunger lid
- Safety: certified BPA free
- Care: hand wash in warm soapy water, not dishwasher or microwave safe
- Packaging: plastic-free gift boxes
Who the ROK Zero Jar suits
- Coffee drinkers who buy whole beans: it keeps an opened 250g bag sealed between grinds.
- Homes with two coffees on the go: one jar for a morning espresso roast and one for a decaf, for example.
- Gift buyers: the two jars arrive in their own boxes, so they are ready to wrap.
For more presents for coffee drinkers, see our gifts for coffee lovers.
The limits
£49 is a lot for two jars. Airtight coffee canisters on Amazon UK start at about £12, although those trap the air inside rather than pushing it out.
Each jar holds one 250g bag. So if you buy coffee by the kilo, you will need four jars, or you will still have beans sitting in a bag.
The jars are not dishwasher or microwave safe, so they need a wash by hand. Also, ROK says to wipe coffee dust off the O-ring now and then, because grounds stop it sealing well.
Finally, the glass lets light in. So keep the jars in a cupboard rather than on a sunny worktop.
Where to buy the ROK Zero Jar in the UK
ROK sells the Zero Jars direct, and they come with ROK's 10 year warranty. Buy Me Once, the shop for products built to last, sells the same pair for £49 too. The ROK Zero Jar page has the care instructions and a video of the plunger at work.
FAQs
How much is the ROK Zero Jar?
£49 for a pair at ROK and at Buy Me Once.
Is the ROK Zero Jar a vacuum jar?
Not quite. Instead of pumping air out, you push the lid down onto the coffee, which squeezes the air out past the seal.
How much coffee does a Zero Jar hold?
600ml, which ROK and Buy Me Once say suits a 250g bag of beans or ground coffee.
Can the Zero Jar go in the dishwasher?
No. ROK says to wash the jar and plunger in warm soapy water and rinse them.
Can I store food other than coffee in it?
Yes. ROK says it suits any granular food that suffers from oxygen damage.
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