we needed 45 for the rack from Animal Plastics, the IRIS330(15) 15 SHELVES HIGH, 45 TUBS TOTAL, so we just ordered 3 boxes of 20, to have a few extra in case some break, but i doubt they will, they are not brittle like steralite or rubber made tubs, we use a cheap soldiering iron for the holes ourselves, we prefer melting the holes versus drilling them.