[Omaroo (Chris Malikoff)]

Bill - they're made by me to be an interference fit - i.e. they are slightly too large (by a mm or so) and by virtue of that stay in place very snugly. I make them with abs plastic strips about 14mm wide and 1mm thick - which gives the resistor strip a "backbone" before I encase the whole lot in 25mm heatshrink. I roll it around in a circle and join the ends with more heatshrink (covering the overlapped ends). This circle is just ever-so-slightly larger than the inside of the flange - so that when you push it into place it's help there under tension. Works extremely well.

The last two shots are the same system being used in a 4" refractor and the final is my C8 with dew heater and shield on. In this shot I am actually running nine (9) separate heaters - for 3 scopes, camera lens, an eyepiece, straight-through finder (both ends) and two red dot finders. One 17Ah battery lasts me 2 full nights.