The U4 (G2) has two improvements based on the original U4 carabiner knife,

1)With a blade safety lock; 

2) The carabiner body is unibody which adds strength and durability to the carabiner itself. And the blade uses a standard #11 scalpel blade (5 extra included) for easy and simple replacement. 

Tools the U4 (G2) could be used for, 

1. Keys organizer
2. Keychain carabiner
3. Paper cutter 
4. Utility knife
5. Measurement Ruler