Hi @BobHoel !
The helmet/ rear light combo options that REI has uses a mounting system with the light, unfortunately not a feature with the helmet itself. It’s usually strong Velcro or rubber bike light mount in combination with a bike helmet that has large ventilation holes to put the Velcro through. There are some helmets by Smith, Bern, POC etc that have a clip on the back but the helmets I saw are for goggle straps. I haven’t seen any specifically for lights.
Here are some great options for lights with helmet compatibility. Helmet lights
We can help if you have any questions around those products if you have any, just let us know!
What you’re asking about might be out there (or should be!) but it doesn’t appear that REI has helmets with rear light mounts at this time.