DIY Telescopic pole question - sprung buttons?? Do you know what they're called?

Hi all,

Figured I might as well ask the like minded folk here who prefer to self manufacture as I do. Someone is bound to have the answer.

I'm making some sliding poles - ie. one bit of square hollow section telescoping into another. I want to use those sprung buttons like you see on some telescopic tent poles, paint roller poles, extendible fishing net handles etc.

I've not cut the handle of my bream net off to have a look but I'm guessing they are a presprung button, possibly just bent spring steel that slide up the pole into position on the inner tube.

Questions:

Does anyone know what they would be called in a hardware search on google or in a hardware/fasteners & fittings catalog?

Even better, does anyone know where to get them & what they are called with that supplier?

Any help appreciated.

Thanks,

Dave