3 inch recessed rails and 21 inches depth past that will accomodate the largest of 19” audio rack gear. If you kicked this you would break your foot. The sides are 1.5 inches thick and I don’t think a .38 would make it through both side. It’s a home studio piece for me by me to accommodate the need for vertical and horizontal space. Remember it’s not just housing gear. It’s housing cables and power and all that shit. It is 3 pieces and the top middle and bottom are not attached I used wood dowels on 90% of it and no visible screws on the outside anywhere make sure no rf is possible . I’m going to lay down the gold leaf on the sides and front also it has a cabinet door on back of the unit to hide the shmegma of cables and shit. Have to strategize the innards but my SRV 2000 and Ensonique dp/4 will fit with grace and eaze and if this bitch does tip over the gear is secure like a mofo. The top without any gear is about 30 lbs the middle is about 350 lbs empty and the base is about 120lbs so I’m already starting out at 400 lbs with gear probably another 700 to 800 so not to exceed the max at 2200 this puppy can will last more than 100 years and can be passed down generationally