Plate measures 65mm X 65mm. Handy if you need to mount a shielded 9 pin miniature J-slot ceramic bodied tube socket for 12AX7, 12AU7 etc. to your chassis. Please note that these plates are fabricated on automatic machinery with not a lot of attention lavished on an elegant finish. There are typically some small scratches and marks in the matte finish.The bottom line? These plates look good enough for most D.I.Y. tube amp projects but if you're really fussy you may want to make your own plates.