Help~Elastic for waist band

[mamaofthreeboys]

Now I know I saw it post suggesting using elastic in the waist band.
My son's pants are a bit too loose in the waist so I think this will be necessary. Still playing the wait until we're completely dry game from washing/lanolizing. Anyways.......

Which kind would I use and what exactly am I looking for? Where would I get some?
Joann's or a fabric store?

TiA :chef

[mommomrebecca]

Get the swimmers elastic from fabric store, for the moisture. I've used regular though and it's fine.