1. I find the Vise-Grip slightly firmer than the Contour Power grips yellow, except the transparent ones which seem equally tacky.
2. Vise-Grips are also slightly larger for the same size.
With Contour I use 25/32" and 3/4". Vise-Grip's 25/32" and 3/4" are too large for me. I use their 49/64" and 47/64".
3. Different colors in Contour have different firmnesses. I find the red and silver firmer than the yellow, purple, and the orange, which I prefer. The red were almost inflexible and tore easily when I tried to put shims in the back of the hole for sizing.
Nowadays I stick with Contour's yellow. It just makes life easier.
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"None are so blind as those who will not see."