Speaking to an ex-plumbing mate, he recommends the Hydroseals, and pointed out it has a pinhole which puts water pressure on the o-ring to make it seal, which is the feature I liked in the Doust washers.
Extra product information
. The valve uses hydraulics to make the seal. As the tap closes, hydroseal takes the force of the water and turns it back against itself.
. Water flows through the hole and builds up pressure behind the "O" ring, forcing it down onto the valve seat and moulding it to any imperfections in the seat.
. Available from plumbers supplies; listed in Yellow Pages.