The Thudguard helmet is ideal for babies who are still less than sure-footed when developing their newfound mobility. Learning to walk on hardwood floors, tiles, patios or near hard furniture can cause painful accidents. The helmet is lightweight, sturdy and comfortable plus has been impact tested and endorsed by emergency and medical experts. The Thudguard hat is designed to absorb and reduce the impact of head injury due to fall or collision from a child's own height. It has an adjustable soft elastic chinstrap and is made of ultra lightweight foam and materials to avoid pressure on developing neck muscles. .75 inch thick impact tested foam to absorb severity from bumps. A comfortable stretchy circumference band allows for growth and holes and air channels on inside of helmet for ventilation. One size fits all. Helmet design eliminates the need for sizes S/M/L. (16? circumference plus 4? provided by stretchy band.)