"There's not much you can say about a spanner. It fitted my CH pump nuts perfectly - there wasn't enough room around them to use an adjustable wrench or even one of the rubber-band tools. It seems pricey for a single spanner with limited uses but it looks and feels like it will last several lifetimes and its still cheaper than calling a plumber out."
"i use 2 of these everyother day - for the money they have become priceless overtime. as many others have said it will not always fit but in my experience you can normally weasel it onto the pump nut one way or another.
ideal for putting new valves on.
great tool for powerflushing adaptors
perfect for getting that last little tighten
also perfect for the extra leverage on stubborn old valves (with a little heat ;-)"
"Bought 2 of these to remove my thermal store circulating pump, the jaw gap is variable as others have reported, at the open end one was 52.5 mm, the other 51.7 mm (not great for a 52mm pump nut!), the first one fitted well, the second would not "slide" on to the nut, I had to lower it on from above and it was tight but just fitted, it seems that the majority of the opening is about 52mm but the gap at the open ends does vary. Glad I got the two! Pricey at £20 each given the variable gap opening."