Size and specification are the item
A carton is defined by its dimensions and its ply, film by its width and micron, tape by its width and length. A customer reordering expects exactly what they had last time, and a generic item list guarantees they will not get it. Keeping the full specification on the item means a repeat order is a lookup rather than a conversation.
Three units in one catalogue
Cartons sell by the piece, stretch film and strapping by the kilo or the roll, and bags sometimes by weight and sometimes by count. Holding the unit and conversion on each item means a mixed order bills correctly and the stock figure counts what is actually on the racks rather than an abstract quantity.
Repeat orders from manufacturers
Your customer is usually a manufacturer ordering the same specification every month, which makes the previous order the fastest route to the next one. Opening the party and repeating what they took last time saves a call and prevents the specification drifting. It also tells you when a regular customer's volume has dropped, which is worth a phone call.
Monthly accounts and delivery
Packaging goes out on regular deliveries against monthly settlement, so the account is a running one and the delivery record is what a customer's store checks against. Recording each despatch with counts, and sending a statement at month end, is what makes the account verifiable rather than something their accounts department queries.