Help finding special sanding pad.

Can anyone here help me find where I can buy those thin flexible sanding backing pads (not like the thick power pads) uses on such jobs as making fins or sanding down future/FCS plugs etc.

The ones I have seen were made of thin brown fiblerglass and were semi-flexible.

Thanks to all for any help.

 

Harbor Freight…  Seven inch screw on.  Lowel;

i got one at lowes. 3M made. Cheap too about 15$. It was a 6in pad. They also have one without threads for your drill, imo very handy when making fins. 

Heres an example of what i mean

Angus-