If you have boxes, and trays, which are slightly different or conical, then you can use the avancon ZPC roller conveyor system with 2 rows of double conveyor-rollers.
For different sizes of goods - as very small, large or mixed cartons - you may use the full width avancon "multiblock" conveyor-rollers made with or without soft tires of Polyurethane.
If you have boxes, and/or trays in different sizes or conical, then you can use the avancon ZPC system with conveyor-roller-corpus and spacers. These conveyor-rollers can be delivered with or without tires of softer Polyurethane and run very quiet.
This avancon roller conveyor-system can be made with a
min. pitch of 40 mm. That
means you can transport very small goods from 120 mm
length without having to use rollers of smaller diameters. These roller-corpus are also available as friction drive for low pressure accumulation and partly in curves.