GSI Outdoors
GSI Outdoors MicroLite 350 Flip Vacuum Bottle
- Weight for its size: 2/10 How much it adds to your pack for the water it holds.
- Packed size (empty): 3/10 How much room it takes up when it is empty, for the water it holds.
Short walks and commutes that need a slim, leakproof insulated bottle that fits a car cup holder
- Type
- Insulated
- Capacity
- 0.35 L
- Weight
- 204 g
- Keeps hot (maker's figure)
- 8 h
Packed size 0.58 L, 18 cm long and 6.4 cm across Compare with a 2-litre bottle
Shorter than a 2-litre bottle and thinner than one. Drawn to scale.
Where to buy
Basecamp Gear £31.99 In stock. Free delivery. Separate UK company (BasecampGear Ltd, Billingham) with its own checkout. Shop shows RRP £32.99. The page says 'Available to Order', though its stock data says in stock. Free UK delivery over £15 (Royal Mail Tracked 48).
View at shop: Basecamp GearUltralight Outdoor Gear £31.99 In stock. Free delivery. Shop shows RRP £32.99. Lists 202 g and 350 ml. Free tracked UK delivery on all orders.
View at shop: Ultralight Outdoor GearPrices checked 8 Nov 2026 on each shop's own page; shops can change them. We earn no commission on these links; shops are listed by price. More
Our ratings (out of 10)
1 to 10, compared with the whole market. Each says what it's based on. How we score
Weight for its size
From maker's figures 2/10How much it adds to your pack for the water it holds. 2: A weak point.
GSI's page text gives no weight; its product data lists 204 g for 0.35 L: 583 g per litre, over 500 g/L. The figure matches Ultralight Outdoor Gear and Basecamp Gear (202 g, 577 g per litre) and Advnture's spec table (200 g, 571 g per litre), so the band is the same on every figure.
Packed size (empty)
From maker's figures 3/10How much room it takes up when it is empty, for the water it holds. 3: Below average. Fine for some trips, not others.
A rigid bottle does not shrink, so we draw it as a cylinder from its height and width. GSI gives three dimensions and no body diameter; converted, they are 18.0 cm tall, 7.4 cm and 6.4 cm. In GSI's front-on product photo the bottle is 0.35 times as wide as it is tall, which matches 6.4 cm over 18.0 cm (0.35), not 7.4 cm (0.41), so we take 6.4 cm as the body. 3.1416 x 3.2 x 3.2 x 18.0 = 579 cm³, so 0.58 L empty for 0.35 L held (1.66 per litre), in the 1.3–1.79 band. If the 7.4 cm figure were the body it would be 0.77 L, 2.21 per litre, band 1.
In short
Good for
- Short walks and commutes that need a slim, leakproof insulated bottle that fits a car cup holder
- One-handed drinking from a flip top while holding a map, pole or phone
- A hot or cold drink at a day camp, when pack weight matters less than a small, tidy bottle
Strengths
- 2 mm walls give a slim body: 18.0 cm tall for 0.35 L (GSI)
- Push-button flip cap locks shut for travel and locks open to drink (GSI); Advnture could not make the lid leak
- Advnture's test: boiling water had cooled to 68 °C after four hours
- Lifetime warranty against material and workmanship defects (GSI)
Weaknesses
- 204 g for 0.35 L: 583 g per litre, in the heaviest weight band
- 0.58 L of pack room for 0.35 L of drink
- GSI's own page says 12 hours hot and 24 hours cold in its intro and 8 hours hot and 16 hours cold in its feature list; we show the lower 8 hours
- Advnture notes a very hot drink is too hot to swallow straight from the flip spout, so a separate mug is needed
- No second independent review was found, so ease of use and durability are estimates, not reviewed scores
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.