I made the foil insulated personal wallets after I heard that cash can be easily stolen from those 'air waving' credit and debit cards, or some can scan whatever card you have on you with a petite device...
Imagine that!!??
Works like a charm, nothing goes through it.

Another benefit?
I made a bigger one for my phone.So whenever I want to be 'out of a reach' I just put lil bug in a wallet.
hehehehe