We are printing using a VersaUV LEJ-640 using the EUV4 inks. I have a project that I would like to use a primer cartridge. When reviewing Rolands site, they show ECO-UV4 has CMYK, WH, GL and PR. However, I cannot find the primer anywhere except under ECO-UV. Is this a compatible cartridge and/or is there a primer really available for the EUV4 ink set?