At only 18g you'll be hard pressed to find a bottle cage that weighs less than the Pulse L2 for the same price. More importantly than that of course though is that it holds the bottle in place at all times; no matter what the conditions are. 
Thanks to the advanced make up of carbon fibres used in the cage and the multiple points of contact, it grips whatever bottle you're using no matter what terrain you're on. It's also incredibly strong due to the high level of reinforcement used to back up the contact points to prevent it breaking.
Features:

Super Lightweight: Only 18g
Highly resistant Carbon Fibre
Top Design: Easy to insert and remove the bottle
Universal: Adapts to different bottle diameters
Comes with Light aluminium screws