Castles S1F4 MAX DUO
The MAX with a second screen on the back — a 1.9-inch customer display for QR payment and confirmation.
- Manufacturer
- Castles
- Form factor
- Portable
- Operating system
- Secure Android 13
- Connectivity
- 4G LTE, 3G, GPRS, Wi-Fi 2.4 + 5GHz, Bluetooth 5.0, USB-C
- Receipt printer
- Built in
The DUO is the S1F4 MAX with a 1.9-inch colour display added on the reverse, facing the customer. It carries the QR code for a wallet payment and shows the amount, so the merchant does not have to turn the terminal around.
The main screen stays 6.7 inches at 1600 x 720, on an ARM Cortex A75 and A55 octa-core at 2.0GHz with up to 64GB of flash. Cameras run to 13MP with autofocus as an option.
It is 192 x 81 x 54mm and 475g, fifteen grams heavier than the MAX for the extra screen. PCI PTS 6.x, 3350mAh, 58mm paper roll at 90mm a second.
What it costs
The rate you pay is negotiated on your volume and card mix, not set by the terminal — two businesses on the same S1F4 MAX DUO can be paying very different money. Find out what yours should be.
Other Castles terminals
Specifications from Castles. Checked 3 October 2026.
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