These are LED drivers that give a constant voltage of 24 volts.
Calculate the power requirements of the length of LED strip you are installing by multiplying the length of the strip in meters by the power per meter of the strip.
For example if you are using a 2.7 meter length of 15 Watts per meter LED strip the power required will be 2.7 x 15 = 40.5 Watts.
Choose a driver that is the next higher in power to the wattage required for the length of strip. In this example it will be the 60 watt driver.
These drivers are Talexx brand from Tridonic and are made in Germany. They can be mounted in a convenient position as long wire runs are not a problem