The Axomat 5a Black & White is a deluxe version of the "Standard" model. The advantages are; a taller column (allowing greater magnification), a larger baseboard, extensive lens plain adjustments for the correction of line distortions on your negatives (Sheimpflug rectification), a metal negative carrier with an ingenious split line focusing aid and the ability to lock the carrier ajar while still inserted into the enlarger head: enabling rapid negative changes.