Quick answer
Replace your Fellow Duo carafe glass when you see cracks, chips, or any damage that compromises its integrity. The genuine Duo Replacement Glass is borosilicate and resists thermal shock, but physical damage requires immediate replacement.
Why borosilicate glass still needs replacement
The Duo Replacement Glass uses borosilicate glass, which has a very low coefficient of thermal expansion. That means it handles sudden temperature changes — like pouring hot coffee into a cold carafe — without cracking. But no glass is immune to physical impact. A drop, a knock against the counter, or a hard tap during cleaning can create small cracks or chips that grow over time.
Even a tiny chip near the rim or base can weaken the structure. Once damaged, the glass cannot be repaired. Continuing to use a cracked carafe risks breakage during brewing, which can spill hot liquid and create a mess or injury. Replacing the glass is the only safe option.
Compatibility check before you buy
The Duo Replacement Glass is only compatible with the 2nd generation Duo, sold after October 2015. If you own an original Duo from before that date, this replacement glass will not fit. Check the bottom of your brewer or the original packaging for the manufacturing date. If you are unsure, contact Fellow customer support with your brewer's serial number.
Also note that the replacement glass does not come with the grey silicone bootie. If your bootie is worn or missing, you will need to reuse the old one or purchase a separate bootie if available.
Diagnosis and replacement guide
- Symptom: You notice a visible crack, chip, or star-shaped fracture on the glass carafe. You may also hear a faint clicking sound during brewing or see coffee seeping from an unexpected area.
- Likely cause: Physical impact: the carafe was dropped, knocked against a hard surface, or struck during cleaning. Thermal shock is unlikely with borosilicate glass, but a pre-existing weak point can propagate under heat. If you cannot recall an impact, inspect the carafe closely for hairline cracks that may have started at the rim or base.
- Corrective action: Stop using the carafe immediately. Order a genuine Duo Replacement Glass (product ID 41461). When it arrives, remove the silicone bootie from the old carafe, insert the new glass, and reattach the bootie. Ensure the glass is seated evenly before brewing. Do not attempt to glue or seal cracks. Replace the glass only.
- Stop or choose another option: If your Duo brewer is a 1st generation model (sold before October 2015), this replacement glass will not fit. In that case, contact Fellow customer support for alternative solutions or consider upgrading to a newer Duo brewer. Verify your brewer generation before purchasing the replacement glass.
Product facts
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Duo Replacement Glass: Duo’s borosilicate glass carafe has an extremely low coefficient of thermal expansion, making it resistant to thermal shock. This means you do not need to worry about the glass cracking from hot or cold temperatures during normal use, but physical damage still requires replacement.
Duo Replacement Glass