I love having wrist straps on my larger wallets -- it's SO nice to have your hands free! But never thought it necessary for the smaller bifold wallets 'cuz they are so small. Anyways I was asked to add a shoulder strap for one. I sorta thought it would look clunky, but I was wrong (as I am many times).Basically, a single D-ring was added (figured two would be overkill) so the shoulder strap can be removable.
The strap can also be attached to the zipper pull, but it's more lopsided.