The Ridge Wallet is designed to be used in your front pocket, but I’ve also used it in my back pocket with no issues. Because of its small size, it tends to move around more in my back pocket, where storing it in my front pockets allows the wallet to stay in place more.
If you tend to sit on your wallet, The Ridge is best used in your front pocket so the hard exterior case doesn’t cause issues with your back, bottom and posture.