What does this gauge mean?

I am looking at knitpicks for some yarn and many of the choices express the gauge as:
Gauge: 6 sts = 1" on #3 - 5 needles
What does this mean? Is it #3 or #5 needles? Am I reading this wrong?


They usually give a range of needle sizes, some people knit tighter than others and may have to use the larger needles to get the same gauge. Loose knitters may have to use the smaller ones.