What is the difference between GU10 and GZ10?

Posted by Waston Chen on

The GU10 and GZ10 lamps was by origin made for halogen 230V, where the “cone” base of GU10 made this lamp possible to use in both sockets for GU10 and GZ10 - and had Alu reflector. The GZ10 lamps was Dichroic which meant that this had an advanced mirror which reflected the light and “not” UV (heat) in light direction. To reduce hazard for heat into ceiling in downlights, it was not possible to use the “square” base of GZ10 in an GU10 downlight.

GU10 and GZ10 are probably the best known fittings for spotlights. Lamps with a GU10 and GZ10 lamp base have two pins at the bottom of the lamp. These lamps are locked into the lamp base with a 90 degrees clockwise twist.

The difference between GU10 and GZ10 lamps lies in the bottom side. GU10 bulbs have a rounded bottom, while a GZ10 bulb has straight lines. As a result, a GU10 lamp fits both in a GU10 as in a GZ10 fitting, while a GZ10 only fits in a GZ10 fitting. Hence the letter ‘u’ – which stands for ‘universal’ – in its name.


  • GU10 lamp fits in a GU10 fitting.
  • GU10 lamp fits in a GZ10 fitting.
  • GZ10 lamp fits in a GZ10 fitting.
  • GZ10 lamp does NOT fit in a GU10 fitting.
  • Difference_with_GU10_GZ10

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