A flask that can take a knock without shattering is worth its weight on any trip where things get a little rough around the edges.

The GSI Boulder Flask is built from shatter-resistant co-polyester resin with a grippy silicone bumper wrapped around the outside. That combination means it can survive a tumble on rocks, a drop from a canoe gunwale, or a rough rummage through a drybag without cracking. It's also completely BPA free, so what goes in stays clean.

The wide mouth makes it easy to fill, pour, or drink straight from the flask, and the hinged silicone cap stays attached so you're never hunting for a lid at the end of a long day on the water. Moulded graduation marks on the body let you measure as you pour, a small but useful touch. At just 4.1 oz, it adds almost nothing to your kit.

• Capacity: 10 fl. oz. / 296 ml
• Weight: 4.1 oz.
• Material: Shatter-resistant co-polyester resin
• Silicone bumper and hinged silicone cap
• Wide mouth opening
• Moulded graduation marks
• Hinged cap cannot be separated from flask
• BPA free