They are good sprayers but John's point is a valid one.
As I recall, John's company sells an improved version of the sprayer to include more sturdy, brass fittings, for use within the CC industry.,
The only issue I've had with the plunger being when the vent became stuck between coats, whilst to being used for spraying acrylic sealer. This in turn caused the rubber bung / seal at the bottom of the plunger to blow due to a build up of too much pressure. This was replaced at no cost by Solosprayers. They are a good supplier and can be trusted to offer good advice and back-up.