The outside of this crochet hat is made with neon green 100% polyester yarn and multicolor 100% anti-pilling acrylic yarn. It has a polyester olive green leaf ribbon trim sprinkled with polyester multicolored mini flowers, and is topped off with one tiny gold-plated mini shamrock. It is lined with 100% cotton. Wear it out on a sunny day and watch it glow in the dark at night. When the glow fades away, just shine a flashlight on it for it to glow in the dark once again. It measures 19 inches and does not stretch. Hand wash recommended or wash it inside out with like colors on a gentle cycle. Do not bleach. Hang dry recommended.