E6 introudces the plastic nylon Injected mold seat with a carbon seat post.  This is the lighest seat on the market.  
 
The Pro seat is offered in two seat sizes standard, and X-Lite.   The Pro X-Lite seat is a smaller seat for riders that are looking to save every gram possible.  The Pro X-Lite seat is the same seat used on the 22.2 and 25.4 mini seat combos. 
 
Weights: 
27.2 Standard - 115G
27.2 X-Lite - 90G
25.4 - 80G
22.2-  80G