In short, the Element was designed to work with almost any kind of floss. This includes flat, monofilament, string, and multifilament floss.
In fact, we tested over 10 different types of floss so far.
Generally speaking though, we strongly recommend that you use a high quality monofilament or tape floss with the Element. Monofilament floss doesn’t unravel or split apart, unlike multifilament floss that unravels like strands of yarn or splits into multiple strings under stress. Tape floss is very flat, like a sheet of paper, and rarely splits apart either if it’s made out of high quality material.