Based on the average monthly print volume of about 150 pages (ET-2550). 300 pages (ET-4550) and 800 pages (WF-R4640):
1738625 - EcoTank ET-2550 includes enough ink to print up to 4,000 black pages / 6,000 color pages
1752252 - EcoTank WF-R4640 includes enough ink to print up to 20,000 black / 20,000 color pages.
1738623 - EcoTank ET-4550 includes enough ink to print up to 11,000 black pages / 8,500 color pages.
Epson Expression ET-2550 EcoTank Wireless All-In-One
Epson WorkForce ET-4550 EcoTank Wireless All-In-One
Epson WorkForce Pro WF-R4640 EcoTank Wireless All-In-One