I though I had purchased a splitter that could be used with a 9v Boss type power supply. Turns out it can't be used like that, the plugs won't fit. It can only be used as a splitter from the 9v dc power output on a Boss tuner. My mistake, I should have checked the specs better but it's something to be aware of (and to be honest I think the product description should have mentioned this).
The quality is decent for the price. Nothing outstanding but slightly more robust than the cheapest 9v power cables out there.
Recommended, but make sure you know what you're buying.