SR= Side reversed to interlock your cards, a thinner way to ,make your wallet thinner when full and no you would not loose your cards. Just try my thoughts in design and have been making this side reversed since year 2000.
8 credit card pockets plus an extra 4 cards sleeves under the credit cards panels (12 cards)
2 Back separated inside compartments for your currencies and invoices.
If you want the No 720 SR not in this standard width then get the No 720US SR 1cm narrower.
My most popular gentleman's wallet, made with handcrafted Premium calf leather, fully leather lined with goat skin leather. Suitable for any world currencies and credit cards, it fits comfortably in your pocket.