The easy solution is to drill a small hole large enough for the probe to fit through and hot melt glue it over the middle of the heat source and glue the wire down too. The probe MUST not move!!! very securely adhere it. (you can always remove it with a thin blade later) I know a lot disagree with this but it is the way that Dion at herpstat recommends the units be used. The temps are much closer than mounting it to the heat source as the temp of the heater has no direct relation to the interior temps. Some claim that pee or poo on the substrate over the probe will cause a overheating I have twice had poo on a probe and the resulting spike was 3 degrees for 10 min. Not really too much of an issue. The only issue is there is some loos to the glue and substrate but in my experience it is only one or two degrees. I use a 91.5º set point and it delivers 90-91º temps. I am not sure however how to deal with a RHP.