This cap is a non-optional accessory to replace the "Child-Resistant" cap now standard on MSR fuel bottles. Required, if you value your life when the stove MUST work.
When you are cold, and your hands are cold, you need the stove going R-F-N, not after you fumble with "push and turn while pushing" clutch-based tighten-only fuel cap. Got sand in the cap? Too bad it won't open without pliers or too
This review was written in the old system and had content requirements that are different than reviews written today.