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