I installed pairs of these nicely made bargain posts on my single ended 300B amps over twenty years ago and they're still working away. This flexible plastic version works better than the old hard plastic version because it's almost impossible to crack these by over tightening. Drill a pair of just slightly larger than 1/2" holes 3/4" apart, fasten everything to your metal chassis with the included hardware, wrap and solder your transformer secondary leads to the bottom of the gold plated brass posts and you're in business. Tops of posts accept single or double banana jacks but I prefer forked lugs soldered to the ends of high quality speaker cables.