Size: (57-62cm)Helmet inner width: 18cmUltralight, about 300gGender: Men, WomenMaterial Outside: PC, Inside:EPSCertification: CE EN1078Unicase technology ,more safe and perfectStorage advice:Do not stored in damp environment, near where the heat source or directly in light, helmet for dry processing, suggest using canvas package for storage.Impact protection:Ventilation,use air cooling make the air freeAnatomic design , senior double-sided velvet protection padEasy to use,with magic buckle connection