What features would be most valuable in a water bottle designed for construction crane operators who work at heights all day?

Construction crane operators work at extreme heights with limited opportunities to refill or access water. What feature would be most valuable in their specialized water bottle?

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Insulated design that keeps water cold for 24+ hours
One-handed operation with secure locking mechanism
Large capacity (1+ gallon) to reduce refill frequency
Built-in communication system to contact ground crew