Here's a really handy accessory for tube experimenters. Stainless steel plate measures 1.691" X 1.413" overall. Socket hole .881", tube socket screw mounting centers 1.275" but the slots allow for fooling around. I measured 1.125" centers between the two chassis mounting screw holes. Please note that these plates are stamped out on automatic machinery with not a lot of attention lavished on an elegant finish. There are some small scratches and marks in the brushed finish. I tried installing a number of the fine sockets we sell on this plate and most fit pretty well. To mount the plate with tube socket installed on your compatible chassis you will need to perform two modifications. First, you will have to notch the octal socket hole in your specific chassis to allow clearance for the fastening nuts. You will also probably need to drill or Dremel two tube socket mounting holes in your chassis simply using the two holes in the conversion plate as a drilling guide. Please check the measurements we've provided to determine if this plate will work your specific chassis. We include photos of tube sockets on this page to illustrate how the plate is used. Tube sockets are NOT included in this sale but are available as separate items.