I am not sure what you mean but any submersible Can be set into a bottom mounted sleeve of high plastic a few inches long (Slotted for water flow) and you can also superglue a Rena or Visa-therm to a base platform set into the substrate.
P.S. Welcome to MFK.
I USE A HYDOR UNIT THAT IN-LINE WITH THE DISCHARGE HOSE FROM MY CANNISTER FILTER, WORKS GREAT KEEPS TEMP PERFECT NEVER CHANGES AND NO MORE BROKEN IN TANK HEATERS