These lamps have 4 pins in a row and are easily identified. They are designed for use in flat light fittings either wall or ceiling mounted.
They are also known as a PL-F lamp
Just match the wattage and light colour and you cant go too wrong!
The shape makes for a very even spread of light
Being triphosphor they don’t go “creamy” with age and last a very long time
They can only be used in fittings designed for these lamps