I grew up in Florida, so summer = flip flop tan lines to me...
These markers measure approximately 1/2" (12 mm) long by 1/4" (5 mm) wide, and weigh less than a gram.
They are shown on an 8 mm ring and a 12 mm lobster clasp. The 6 mm ring comfortably fits knitting needles size US4 and smaller. The 8 mm ring comfortably fits knitting needles size US6 and smaller.