A slide rail assembly for a rack system is installed to a chassis. The chassis includes a first chassis and a second chassis. The slide rail assembly includes an outer rail and an inner rail. The inner rail is movably connected to the outer rail. The first chassis of the chassis is installed to the inner rail, and the second chassis of the chassis is movably connected to the inner rail. The second chassis is movable relative to the first chassis to adjust the total length of the chassis.