Carhartt Rain Defender 21L Classic Backpack

How durable is the material if I'm using it on a construction job site?

It is built for tough utility. It is crafted from 600-denier polyester with Carhartt’s Rain Defender® durable water-repellent (DWR) finish, which causes rain and mud to bead up and roll off the surface rather than soaking in.

Does it have any safety or visibility features?

Yes, it features reflective edge binding on the sides of the pack and reflective material on the zipper pullers, which provides a helpful touch of extra visibility if you are walking to your vehicle or job site in early morning or evening hours.