Internal volume is slightly smaller than expected due to some reinforcement bars, but it was a smart design sacrifice to create a durable and weather resistant product. For my application I had to drill a couple of holes (.625 and .25) to pass the camera cables through. The material was hard without splintering and malleable without abrasion. The strength and structure of the box was not affected at all by the holes. I was pleasantly surprised to find that the mounting holes for the box were well designed for a solid mount (pretty critical for a camera) and the gasket was the perfect length not to stretch or cut.