What type of dimmer switch?

[tgif]

I want to use a dimmer switch to control the brightness of some halogen lights. The bulbs are marked: Philips Twistline Alu 50w 120v 250 F5.
The fixture is not labeled with anything.
Do these bulbs require a dimmer switch with a magnetic or electronic transformer? Or do I use a dimmer made for incandesant lighting?
Thanks for the continuing advice.

[HayZee518]

the bulbs are marked 120 volt so just about any type of dimmer will work. if the halogens were part of a low voltage circuit then a special dimmer would be needed because of the low voltage transformer.