The advanced radiation suit is a suit specially designed to stop radiation. It covers the entire body, making it impossible to wear a helmet or glasses with this clothing.
It has the same appearance as a normal radiation suit, but has 33% higher radiation resistance. It is also more durable (25 item HP, compared to the ordinary radiation suit's 15) and has a higher DT (8 rather than 4).
Crescent Canyon - may appear as a random item in an armor case case near two wrecked cars.
The advanced radiation suit can sometimes become mysteriously unwearable. Its condition will be within the acceptable range, or it may even be damage-free, but it will still be grayed out in the Pip Boy as if it were too damaged to wear. (A similar bug affects the space suit.) One solution that seems to work is to drop the suit onto the ground and then pick it up again. Once it re-enters your inventory, it should be wearable.
When the suit is in Boone's inventory (but not worn by him) he will not wear any hats or glasses.