What connectors do i need

[markyyyyyy]

I currently have 2 x a 15mm central heating flow and return pipes with a stop end on each of them

I want to connect 10mm flexi pipe to the 15mm pipe, run it behind the wall and pop out to connect to the radiator valves as below. I have approx 1 to 1.5m length to get to valve on rad

What fitting do i need:
A) to connect from 15mm copper pipe to 10mm flexi pipe
B) to connect the 10mm flexi pipe to the radiator valve (as pic below)
Is it just. Standard 10mm to 15mm elbow?

Whats this white plastic bit that fits into valve called?

 

[Madrab]

I presume you are talking about 10mm plastic pipe, not flexi pipe?

Yes a 15mm to 10mm reducer. You will need inserts for the respective sized plastic pipe.

The white plastic ring is the push fit locking mechanism for the valve, you push the white ring in towards the valve to remove the plastic pipe.