Jason S.wrote a review of Park Tool BBT-47 Dual Sided Bottom Bracket Tool on May 9, 2019
This tool is well constructed and attractive. I picked it up to install a Wheels Manufacturing inboard bearing T47 BB in my new frame. I've used BB tools of a similar design (i.e. a cup-like splined tool to be used with a socket or torque wrench) before, with mixed results. While these type tools fit the splines on the BB cups just fine, the flaw is that when it comes to applying final torque with a wrench attached, it's very difficult to keep the tool aligned with the splines without it rotating off. Unless you're careful (and have enough strength to simultaneously hold the tool aligned with the splines while applying torque) the BB cups are scarred by the tool and the edges of the splines rounded off. It's just not a good design. That said, part of the fault also lies in the design of the BB, as well, since the splines are only about 1.5mm deep--just not enough material to facilitate good engagement. Regardless, I think tools like the BBT-9 are much easier to keep in place while applying torque because you don't need to simultaneously apply force in two directions. I found out after ordering this that Wheels Manufacturing makes such a tool (double ended BB tool), which is also half the price of this one. I would recommend going that route--if I'd found it earlier, I certainly would have.
My install resulted in a marred BB cup and a big paint chip on my downtube from the tool flying off the BB because I was unable to keep the splines engaged while applying torque. Real bummer.