Hi evyatar -
to Reef Sanctuary and the RSM Club!
I had looked at the CPR overflows and was doubtful that the inner box would fit the RSM 130, so I got the Lifereef overflow that was designed specifically for the RSM. I'd also heard that the CPRs had been known to fail once in a while, even with the Aqualifter pump, to restart the siphon after a power outage (flood time!). The Lifereef seems to have a spotless reputation for restarting after a power outage, or after turning the returm pump off and on, and doesn't require any additional pump to get it going. I'm very happy with mine and I think it's what most (if not all) of us 130 owners use that run a sump and/or refugium.