If I “shop by printer” and navigate down to the pro inks for the P400…
Shop By Printer > Epson SureColor Printers > SureColor P400 > Piezography Black & White systems > Piezography Pro
I see that the Pro inks can be used with “supported” 8- or 9-ink cartridge printers. Since I arrived here via the P400 printer, I assume the P400 is one of them. But if I navigate further down into (say) the 60 ml Pro set, I read that the inks are for printers “with at least 9 color positions.”
I think the text should be modified to explain how the inks can be used with printers like the P400 which have only 8 ink positions.