Schwinn Artemis Adult Women Micro Bicycle Helmet (Colors and Graphics May Vary) Adult woman's bike helmet (Colors and Patterns may vary) Easy-to-adjust webbing strap for a comfortable fit under the chin 21 contoured vents for enhanced air flow; heat-sealed pads to control perspiration Visor for sun protection Fits Head Circumference of 54-58 centimeters or 21 1/4 to 22 3/4 inches Dial Fit adjustment system for an easy, custom fit, kindly refer to video for better understanding