This is a durable plastic tray for use in automation, parts handling, assembly line use.

It is made from rugged ABS plastic and has lugs for the purpose of stacking when product is in the tray and is short

or when needing a tray to stack empty and to stand up straight.

SM-29 is the same tray without stacking lugs and does cost a bit less.

Without the lugs the trays may or may not easily stack when no product is loaded in them or the product is shorter than the sidewalls of the trays.