Even small inventories — bottles, parts, supplies — need tracking. The point isn't the count, it's knowing when you're about to run out and what each item actually costs you.
Glo Invoice's product catalog supports stock tracking, cost vs. price, reorder alerts, and bulk CSV import. Selling an item on an invoice automatically decrements stock.
Service line items don't decrement anything — Glo Invoice treats Products and Services as separate types so you don't accidentally count labor as inventory.