One sure fire way of doubling your money is to fold it over once and put it back in your pocket - making the Flip wallets a smart little investment. 
Made of soft calf leather, and stitched all card seams  - making them last twice as long as without { anecdotal evidence only }.  Inside you'll find yourself thick elastic, which unbeknownst to most will ensure your Flip stays in shape and keeps grabbing your cash for years to come  - multiplication and equal signs on either panel, it's an outstanding equation.