There is a newer model with coin-sized batteries. I believe it is smaller and should fit where this one does. I used this on 67 & 77 helmets, the 77 lists the part number as the newer one, but this older one still fits.
The battery box has a connection glitch. I stuck a cardboard spacer, it seems to have fixed the problem. I presume this is addressed with the newer part. The visibility is quite poor in bright daylight. It works decently in overcast, or very visible in the dark.
This would have a 4 or maybe 5 star if it had the updated battery pack and better daytime visibility. Also check out their jaw set, fog proof face shield, and other accessories, they don't advertise any of them but they make a very versatile helmet when you add them.
Jeff's review was a good one but don't wedge a piece of cardboard into the battery area to make the intermittent connection "good" because it will fail. I'd done the same thing with the unit I purchased and today again it wasn't working (after about a month). Closer examination revealed a bad solder joint at one of the lugs on the outside of the battery case. Nothing a soldering iron and a dab of fresh solder couldn't fix and make permanent! Would've given this a five-star rating all around except for this single flaw in the soldering job...