The wood on the Ikea Bror rolling cabinet is not thick enough to hold screws that will fix an extention box and support the weight of plugged-in power cables and adapters. So I designed three brackets to attach the extention box to the inside of a metal side bar. The brackets are mounted with M3x25 bolts and square M3 nuts that fit into the small hole at the back of the bracket. The holes for this particular extention box are 130 mm apart.