Radiator Valves

If your central heating pipe is directly under the radiator valve position then it's simple you need a Straight valve. 

If you have the central heating pipe coming out of the wall or from the side to meet the radiator valve then you need Angled valves. 

Manuel radiator valves you can turn the radiator on and off the heat is controlled by your house central heating thermostat. 

TRV or Thermostatic Radiator Valve has a built-in thermostatic to control the heat independently to the rest of your house.