The Contribution by Product report allows you to look at the revenue, cost, and margin of product line items that have been invoiced. The report lets you analyze product offerings, and helps to identify profitability.

The report is under the P&L section of reports.

The report allows you to filter on:

1. Products that were invoiced in a certain date range.
2. Group the products by product category, product subcategory, product SKU, or manufacturer.
3. Filter on one or more product categories. The default is all categories.
4. Filter on one or more product subcategories. The default is all subcategories.
5. Filter on  one or more product SKUs. The default is all product SKUs.
6. Filter on more or more manufacturers. The default is all manufacturers.

Depending on the Group By filter, the report will be in different groupings.

The four groupings have the same columns. First see  the overall grouping totals. Then open the row + to see the detailed information.
The columns are:

Invoice ID
Date Invoice
Manufacturer
Product Category
Product SKU
Produce Revenue
Product COGS
Margin
Margin &