See Pics below Black is Standard Capacity.
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212XL 603XL 202XL 502XL 34XL 16XL 220XL 18XL 200XL T29XL 27XL 252XL 288XL T206 Refill Ink Cartridge For Epson Chipless Printers
Aliexpress UK
With both sizes, the inks are supplied individually so only the colour used needs to be replaced. Compatibility - WorkForce Pro WF-3725DWF - WorkForce Pro WF-3720DWF. Harmonized System (HS) code 84439990.
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eBay
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Clywenss E34XL 34XL Ink Cartridges Compatible with Epson 34 XL Multipack for WorkForce Pro WF3720 WF-3720 WF3725 WF-3725 WF-3720DWF WF-3725DWF Ink Cartridges, 5-Pack (2 Black, Cyan, Magenta, Yellow)
eBay
eBay
Compatible Printers.
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eBay