This product is an example of the Price Per Unit Pro For WooCommerc (PPU) used in user-defined mode. It’s also an example of Simple product support, as the mulch type can be selected.
Customers can enter all measurements (you can determine which units the measurement is in), and PPU gets the total amount ordered, converts it to your base unit (i.e., cu. yd., cu. ft., or gal for volume), and gets the correct price (based on your unit price).