E-Z Trainer training wheels designed for older adults or disabled people who want to ride a regular bicycle but don't have great balance anymore. I bought these for my husband's electric bike but they don't fit on it because of the hub and battery. Paid $150 but didn't try to attach them to the bike until the 30 day return period ended so I'm trying to recoup some of my money. Google the brand name to watch videos of the training wheels in action.