"These are solid back nuts that I used instead of the plastic ones supplied with a set of bath taps. Watch out if you need two - I had thought that these were a pair but this is a single so you will need to Ryder two for a set of taps."
"After having a number of calls to sort out taps that were twisting out of position when used, I came to the conclusion that in most cases that problem lay with the cheap plastic back nuts usually supplied by the manufacturer.
The plastic nuts are too prone to cross threading, splitting if overtightened or rounding off the hex flats. A brass back nut if used properly with or without a top hat bush will prevent all these problems.
It is worth noting that the 3/4" version is sold singly rather then in pairs like the 1/2" version."
"Not a plumber by trade, but had to oblige customer and replace some basin taps. Purchased split klick centraling washers first, which turn out to be a pointless exercise and waste of money. As I found out - the pathetic plastic top hat washers supplied with the taps, just split on tightening. Bought the split klick top washers next, thought they would be a tight fit around the threaded tap 'bottom' - they are not. Basically they are a expensive strong nylon type tophat washer. So, you still have to buy brass top hat washers like these to secure the tap to the basin. They are expensive, but there is no alternative."