Which Halogen bulb?

[Ranburetta]

LIS/SX headset, standard CEV bulb holder, CEV glass, 12v AC 95/110w stator.

I am looking for a halogen headlamp bulb that has a 'proper' dip beam. There appear to be two types both Bosch bayonet fitting, one described as H4 Ba20d and the other just as Ba20d. The H4 Ba20d has a collar on the metal bayonet where it meets the glass envelope and the other does not. Both have a black end to the glass envelope à la H4 car bulb and it may be an optical illusion but the one without the collar seems to be a little shorter (and is cheaper).

I am looking for quality not necessarily price.

What is your experience - which one should I go for?

Ciao all.