DPN Question-Stopping Sliding Stitches

[Stiney]

Hi everyone,

I was wondering if there was something out there that could be put on the end of double pointed needles to make sure that your stitches don't slide off. I accidentally bought double pointed needles that were a half inch too short for my hat, and the stitches kept sliding off...I actually found some fun tack (the blue sticky stuff to hang up posters) in a drawer and stuck that on the needle ends I wasn't using, and it worked okay, but I don't want the yarn or needles to get mucked up.

So...is there something like this, what's it called, and where can I get some!

Thanks so much!