Each product has its unique code.
This code is made by four parts. There is name of product category, serial number, amount of product and price for rental per week.
AA = product category (e.g. Z-Lockers)
001 = product serial number in category (e.g. 002 = the second product in category)
01 = amount of product avavailable
000 = price for rental per week (e.g. -50 = 50 CZK/week), if there is just 00, it means that price is on request