SR= Side reversed to interlock your cards.
6 credit card pockets plus an extra 4 cards sleeves under the credit cards panels (10cards)
2 Back separated inside compartments for your currencies and invoices.
US= specially designed Like the No 720 SR but for $US currency 1cm narrower called:
No 720 US SR
My most popular gentleman's wallet, made with handcrafted Premium calf leather, fully leather lined with goat skin leather. Suitable for any $ US currencies and credit cards with 2 back compartments, it fits comfortably in your back or front pocket.