Many are under 40 gm. but the Tour 25 is probably the lightest in weight. Most the light weight grips are made of synthetic material similar to Winn grips , I believe Winn has the pattern on the proprietary polymer compound.
I did not like the older model form Winn, but the recent models offered different texture and feel. I still don't like the asking price and the short life span for Winn grips.
One thing about synthetic materials, they won't last as long as the rubber compound , I would accept the blend of the two compounds.