Difference between a ';full set'; of solar nails and a ';refill';?

I have gotten solar nails before but never a ';refill'; I guess because I just never knew what it was. Can anyone explain? Thanks!Difference between a ';full set'; of solar nails and a ';refill';?
full set is putting all of them on from scratch. but nails grow. so after 3 weeks or so there is a gap between your finger and the bottom of the solar nail. you need a ';fill'; to fill in that gap. you can't get a refill unless you had a full set put on a few weeks before.