The SKB 3i-M4U13-FRM is a rugged, 4U injection molded rack frame specifically designed to fit into SKB’s 3i Series waterproof cases, offering reliable protection and mobility for rackmount gear. With a depth of 13 inches, this compact yet durable rack frame is constructed from lightweight yet impact-resistant polypropylene copolymer resin, ensuring resistance to UV, solvents, corrosion, and extreme temperatures. It features a front and rear steel rack rail system with 10/32 tapped holes, providing secure mounting for standard 19-inch rack equipment. Ideal for audio engineers, broadcasters, and field technicians, the 3i-M4U13-FRM delivers superior equipment protection in a highly portable, professional-grade format.