They are typically priced to appear as a good value option compared to the purchase of a single serving, such as a bottle of soft drink, which is likely to incentivise purchasing.
Fel arfer, mae'r diodydd hyn yn cael eu prisio i ymddangos fel opsiwn sy'n cynnig gwerth da am arian o'i gymharu â phrynu un eitem, megis potel o ddiod feddal, gan annog pobl i'w prynu.