Invisigrip
 

I have used it. I think it works well for smaller rulers, like a 6.5" square up or a longer narrow one, I tried it on a large ruler (6X24) and didn't think it helped much. I really like sand paper dots, but they always seem to be right where I'm trying to line something up.

Try dabs of hot glue as grippers.

i have it on all my rulers

I like it on my rulers too. I started off using sandpaper dots, but they would peel off.

I've used and liked it at first but it seems to wear out fast. Now I use
Nexcare Flexible Clear Tape. Works great and cheaper too.

I've used it for a long time and like it alot. Holds nicely, but not too much, so ruler can be moved more easily than with sandpaper dots. Sometimes the edges come loose and it has to be replaced, but still I am very satisfied with it.

I tried Invisigrip and my rulers still slide. I find that TrueGrips works best for me. They are clear circles that look like reinforcements and can be placed anywhere on the rulers.

I bought some and use it on my smaller rulers. If u have a smaller ruler PM me your address and I'll send you some to try on it.

I used it on my older rulers and it worked well enough. just cut it a bit smaller than the ruler. it's sort of like cling wrap, just sticks to the ruler easily but can be removed too.