Fitting - Drill a 14mm hole in your panel or letter face, push the spike lamp holder fitting through the back of the hole and screw the E10 base to the front on the thread of the spike fitting. Easy. The LED or incandescent bulb can be screwed in through the centre of the base and then the cap is screwed over the top. This isn't only a very simple method for the initial fix, it is also perfect for the maintenance of the sign as you only need to be able to get to the face.The maximum thickness of material is 12mm. If your substrate is thicker than this the back will need to be rebated to the correct depth with a 27mm diameter.
Please note. Some batches of lampholders have a '24v' impression in the moulding, these are no different to any that don't have a visible impression, and are perfectly fine for use with 12v, 24v, 60v & 240v.