The climate control knobs on Mazda's RX-8 are notoriously delicate. This is a much more robust version of the fan control knob. Use the metal D sleeve from your original knob and push it into the hole into the bottom of the post of this knob. UPDATED: Has a window for the dash lights to show through so you can see the setting at night. Find the temperature knob here: http://www.thingiverse.com/thing:73813UPDATED: Redesigned the previous knob to have a better indicator and a hole for light from the dash lights to shine through.Use the D-sleeve from your original knobs and drive them into the shaft of these knobs. Before you push the sleeve all of the way in, make sure you index the knobs so the arrow is pointing to the correct location on the fan and temperature indicators. The temperature control shaft has to be thinner than the fan control knob (and more hollowed out as well), so use the knob with the hollowed out backside for the temperature.