Fitment is part of the item
A seat cover, a mat set or a headlamp is made for a specific make and model, and selling the wrong fitment is a return and a lost afternoon. Keeping make, model and variant on the item means the counter can confirm it from the screen, and the invoice records exactly what was supplied — which matters when a customer returns for the same set for a second car.
Installation is where the money is
Fitting an audio system, a camera or a set of covers is skilled work with a real margin, and folding it into the product price makes your goods look expensive next to an online listing while your labour looks free. On its own line, the customer sees what they are paying for and you can see monthly whether the installation bay is actually earning.
Warranty on electronics
Audio units, cameras and sensors carry warranties and come back. Recording brand, model and serial on the invoice means the claim is traceable and the manufacturer honours it. Without that, the replacement is yours, and in this category the items are expensive enough that a handful of untraceable claims wipes out a month's margin on the line.
The number to watch
Stock ageing by model. Accessories date with the vehicles they fit, and a set for a model that has been discontinued does not become more sellable with time. The movement report separates seasonal slowness from genuinely dead stock, and clearing the second group at cost is far better than holding it until it is worthless.