As it is water based you want a mohair or synthetic roller. Sponge rollers like to leave bubbles in water based paint. Two fussy blokes smooth, or arroworthy short pile are both really good. They do a red velour roller too which works well. White coverage in msp could be better, and make sure you give the doors a good time to cure before handling them seriously, because msp likes to stay soft for a while, but it is pretty good stuff.