One K Defender Refit Riding Helmet Liner, Black, Medium

First, the removable liner is a must in a hot climate to avoid stinky helmet syndrome... but I now have a M, L & XL liner which effectively resizes your One K helmet to adjust for various ways to wear longer hair. If my hair is down in a low pony tail, the M takes up some of the space in my L oval helmet, but if I want to wear my hair up under the helmet when it’s really hot & humid, the XL gives the extra hair a place to sit without risking the safety of the helmet. The L works well with my hair in a higher pony tail with the tail sticking out the back. Washes up well in a lingerie bag in the washer & air drying.

Chopped my hair off since I bought my helmet. Had my helmet for a few years so the liner had been worn in a bit. New liner is thicker and made my helmet fit again. Bit pricey but only option.