Periodic Table Original Style Kippah Yarmulke 100% cotton, stays on without a clip, machine washable and reversible! Test Tubes and Beakers on the reverse Proclaim your love of science! Please measure as in last picture, around the widest part of head above the ears: Small: less than 21" Medium: less than 22" Large: less than 23" XL: up to 24" Handmade by Kids Kippot