ThermoBall Vests

Choose a gear capacity 

• Runs under 2 hours: 2 liters 
• Runs 2-3 hours: 2 to 6 liters 
• Runs 3-6 hours: 4 to 12 liters 
• Runs over 6 hours: 6+ liters 

Decide on bottles and/or reservoir 

• Most vests are compatible with both bottles and reservoirs. 
• Bottles are easier and faster to refill, usually holding 500 ml of water each. 
• Bottles can be soft or rigid. Rigid bottles are more durable.  
• Reservoirs hold more water, up to several liters. 

Get the right fit 

• Follow the manufacturer’s sizing guidelines. 
• Choose a snug fit. (Measure your chest while wearing your sports bra.) 
• Leave room for adjustment: The straps should sit in the middle of their adjustment range. 
• Women-specific vests offer fits optimized for the bust and shoulders. 

Which insulation do you prefer?

• Down: Ultralight, warm and packable—but won't insulate when damp and dries slowly.
• Synthetic: Insulates when damp, dries fast and often less pricey than down—though heavier and less packable.
• Wet or humid conditions or high activity? Consider water-resistant down, synthetics or down/synthetic hybrids.

How much will temperature and weather vary?

• Most insulated jackets feature water-resistant shells. Some use waterproof/breathable material—pricier but they eliminate the need for a separate rain shell.

• For high-exertion activities, look for vents in the underarm or core area to dump heat.
• Some jackets vary insulation and shell materials based by body zone to provide weather protection and breathability where needed.

Consider features:

• Hoods: Add warmth and protection; some are detachable or helmet-compatible
• 3-in-1 jackets: Combine an outer shell and midlayer that zip together, so you can wear separately or as one
• Pockets: Designed to stash gear, secure valuables and more.