Just a little more info: When Ma Long was really young he was using Nittaku blades. He used a few but one that stands out is, he used a Nittaku Acoustic for a while. After that he used a Butterfly TB Spirit, then a TB ALC. Then, I believe it was some time in 2011, he did a serious Equipment Junkie Journey where he had DHS design him blade after blade until they designed the 968 blade that he uses now. Once he started using that blade (the commercial version is the HL5 but it is a little different than the 968 blade that he uses) he never looked back.
At that time, Ma Long used Tenergy rubber on his BH. Not too long after the got the blade right, he started having DHS do the work to figure out how to make it so he could use a Red H3 rubber for Backhand. That is where the Red H3 37-degree rubber came from. Once they had a rubber that was good enough for him to use on his BH, he began to only use DHS equipment.
So, again, think about it.

Why did he want to be using DHS rubber on his BH when everyone else (at that time) was using Tenergy on the BH.
[BTW: I have to be honest, I have no idea what ML uses on his BH these days. But I know, when he started using the softer version of H3 on his BH, at first he was the only one. Then when other players saw how good his BH was with it, how he could still do everything he had been doing with Tenergy with the H3 37, a whole bunch of other players started using it as well. ]