Fuji Provia 400 X in my Rollei 35 S. It is the perfect slide film for this little machine, because it eases scale focussing with small apertures at reasonable shutter speed - if it only would not be that more expensive than the 100 ASA ones! But I will continue shooting it as well as other slide film in 135 and 120, hoping that the demand stays high enough so that different slide films stay in production.