Here is a review from the HF website.
Originally Posted by HF User
First use. Seems to work just fine!
I appreciate that HF made this tool! I needed it to test and fill my N63 (550i). It seems to work as expected. I had some difficulty getting a proper seal on the reservoir, but it doesn't seem like that's a tool deficiency. The tool seems robust, like it may withstand moderate impact. The device is heavy, and seems like it's made from dense polymer. The 6 rubber grommets included are various sizes, and designed to fit into the coolant reservoir. The rubber adapters are soft and malleable, which I expect means that they are made from sufficient quality rubber. The tool core, which is tightened to seal the device to the vehicle and act as an orifice to deliver fluid, appears to be made of anodized aluminum. Anodized aluminum seems better than steel in this application because it may have less reactivity with ethylene glycol (and variants). I experienced some trouble when trying to hold a vacuum with the device. Upon reflection, it seems the weight of the attached compressor hose would pull the device slightly ajar, breaking the seal with the reservoir. I realized after I disconnected the tool that may be the purpose of the small hook affixed to the top of the device. Regardless of my inability to use the tool properly, I was able to pull a vacuum on the cooling system, and dunked the intake hose into the coolant bottle. The intake filter fits into a standard coolant jug, but it seemed like the intake filter diameter was too large to fit into a standard gallon water jug. Closing the compressor valve and releasing the coolant intake valve caused the cooling system to drain a jug of coolant. When the first jug was empty, I moved the intake into the next jug, recharged the vacuum, and drained another bottle of coolant. Let the car sit overnight and no visible leaks remained. While I may have lacked the acuity to properly use the tool, it seems like it performed as expected. One negative observation arose from cleanup. When the threaded compressor adapter (nipple) is fitted to the tool and the tool placed in the storage case, the nipple protrudes upwards and prevents the case from closing. So, the nipple needs to be removed for storage and reinstalled when the tool needs to be used. A relatively minor gripe, considering I do not expect to use the tool daily.
Steve