SIlicone check Valve for D&S couplers.
For the larger type check valve see here

'D and S' Type coupler O-ring (Body O-ring) No.5

Normally purchased in increments of x 2. (body takes 2 o-rings)

Keg Coupler - D Type (US Sankey). This is a low profile coupler designed for situations where vertical space is limited.

Includes a pressure relief valve (releases at 55 PSI).

D-Type Keg Coupler - Full 304 Stainless - with Duotight 5/8" to 8mm push fit fittings.

Includes:
1 x - D-Type Coupler with 5/8" Male Beer and Gas threads
2 x - duotight 5/8" duotight to 8mm push in
1 x - Non-Return Ball or Torpedo check piece (Non-Return Liquid)
1 x - Gas Duck Bill valve (Non-Return Gas)

A reusable hop straining bag made from nylon mesh. Good for steeping hops or dry hopping, or for adding other things like oak chips to your brew. It's also easy to clean and sanitise.

Size: approx 125mm x 220mm
From: Krome Dispense

This pump is constructed of food-grade materials and handles boiling wort with ease. The impeller housing is made from polysulfone as it is a tough, food-grade plastic rated up to 120C. The magnetic drive acts as a clutch allowing the user to put back pressure on the pump to slow down flow without any damage to the pump. Since it is magnetic drive, it’s not self priming, you must put the pump under the level of the liquid source.

Pump - MKII 65watt High Temp Magnetic. Note, this is the larger, 65watt model, ideal for large home brew systems and nano breweries. 

This pump is constructed of food-grade materials and handles boiling wort with ease. The impeller housing is made from polysulfone as it is a tough, food-grade plastic rated up to 120C. The magnetic drive acts as a clutch allowing the user to put back pressure on the pump to slow down flow without any damage to the pump. Since it is centrifugal, it's not self priming, you must put the pump under the level of the liquid source.