This is a great tutorial video on how to make sure you are buying the correct size horseback riding helmet, whether you are buying a helmet online or at a store.
The video was put out by Troxel Helmets to assist customers in the proper techniques of measuring head sizes and matching it up with their helmet sizes.
The video goes further and demonstrates how to properly fit to get a snug fit. Troxel helmets are equipped with features that allow adjustments to the width and length of the inner parts of the helmet. Finally, the chin strap of the helmet is to be adjusted to keep the helmet in place and snug.