Regarding function, the product is very good, allowing easy assembly and disassembly of the tuning heads and even of the metal lever (for storage). With this tool, I was able to tweak the tuning of a Yamaha C3 grand piano without difficulty.
The only downside is the high price. Piano tuning is a niche market and this product is priced accordingly. Even with the excellent build quality, if this was a general mass market tool, it would easily cost 1/8th the price.