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. 
 
 Read full article: How to Choose a Running Hydration Vest