Shortly after starting my ebike career, it was clear I needed some sort of mirror. I debated between bar mounted and helmet mounted mirrors. As I don't wear glasses, glasses-mounted models were easy to eliminate. Helmet mounted mirrors seemed attractive in concept, but having dropped Mrs. PDXebiker's bike with a bar mounted mirror and breaking it, I knew I'm not nearly coordinated enough to have a bar mounted mirror. When I asked at my LEBS what they would recommend, their recommendation was unequivocal - the EVT Safe Zone Helmet Mirror. Built by Efficient Velo Tools out of Vancouver, WA (and thus local!), it was only carried locally at the Bike Gallery, so off I went.
The Hollywood Bike Gallery location had them in stock, and even helped me install it while in the store - no packaging to take home. Once the mirror was installed (easy with zipties through ventilation in your helmet) adjusted(intuitive), I quickly fell in love with the mirror.
Easily transferable across the fleet.
Encourages you to wear your helmet.
Easy to scan entire lane by turning head.
I had no idea my helmet bumped into so many things - but its easy to re-adjust.
Walking through doors takes some getting used to.
Available locally at 6 locations of The Bike Gallery and The eBike Store and online at Bike Tools Etc.