Since this is a combination heater/anode, the anode is about 1/3 the size of what you are taking out to put the combination in. (actually, looking at the new packaging it is even smaller!)
It is very expensive (about 100 dollars each time). Hott Rod Water Heater Accessory - PPL Motor Homes
They sell a replacement "Heating Probe" for about 40 bucks; but it is NOT the anode material. You will need to buy a NEW complete unit to replace your sacrificial anode on the Hott Rod.
That means the entire assembly will need to be changed more than 3 times more often than the OEM anode with the same water conditions.
You can buy a lot of propane for that much money in my opinion.
The water heater does not use all that much.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW