The parts, and what they actually do

The sealing ring that sits inside the collar. If the head leaks at the joint, this is almost always why. Buy a five-pack; they harden with age and heat.

A plastic disc with a small orifice that caps flow. If your flow dropped after a head swap, check for one of these inside the inlet before blaming the plumbing.

Conical mesh screen at the threaded inlet. Traps sediment before it reaches the nozzles. Rinse monthly; replace when the mesh tears.

Snap-off face with moulded nozzles. Worth replacing when the rubber tips are torn or the plate is warped and jets angle outward.

Push-in rubber tips for heads with removable nozzles. Fixes a single jet that sprays sideways without replacing the whole head.

Replace when the inner tube kinks or the crimp weeps. A kinked hose restricts flow exactly like a clogged screen — and is easy to miss.

Chrome arm with a 1/2-inch NPT thread. Replace if the threads are crossed or the arm is bent enough to stress the collar.

The valve internals. Only relevant when flow is intermittent with the head removed. Brand-specific — match the valve body, not the handle.

Replacement when the body is cracked or the face is scaled beyond cleaning. Check the gpm rating — a low-flow rain head on a weak supply feels worse than the old one.

Includes hose and bracket. The pause button is useful for navy showers; the flow rating is usually 1.8 gpm.

Splits supply between a fixed and a handheld head. A sticking diverter looks exactly like intermittent flow — test it before replacing the cartridge.

For hose ends and handset joints. Nitrile survives hot water longer than plain rubber.

Explains why scale keeps returning. Above roughly 180 mg/L as CaCO3, descaling becomes a monthly job rather than a yearly one.

The compliant alternative to removing a restrictor entirely. Swap a 1.5 for a 2.0 rather than running with none.