Those are the Pachmayr Grippers. I much prefer them to Hogues, and while wood grips really look nice, they are too slippery for me to maintain with sweaty hands, so the Gripper is the solution. They fit my hands very nicely and even were factory equipped on my Colt King Cobra.
My S&W 10-8 heavy barrel with rosewood finger-groove presentation grips.
I like the look of the grips but they are just too slippery for much use so they are now residing on a 686-1 that needed them more.

My 3" 65-5 357 with Grippers. This is probably one of the most perfect revolvers S&W ever made. A shame it wasn't P&R but at least it's pre-lock and I have a 3".

This is my 66 No Dash 2.5" snub. It's got a set of factory banana grips but I put on this set which was custom made by a company in Bangkok Thailand. A little bigger overall than the original round butt grips and the checkering holds in my hand. At the time I almost passed on buying it because I had already put another 66 on layaway and didn't think I could swing it. Glad I came to my senses! Love this one!