A single row bar has a lower drag profile and a cleaner line on a roof or bumper; a multi row bar puts more output and more optical depth into the same length. The choice is usually decided by where the bar is mounted and what the vehicle has to live with at highway speed.

Bars fail at the ends and at the gland, not in the middle. Sunlitec bars use sealed end caps, a breather to equalise pressure after a hot lamp meets cold water, and a cable gland sized to the loom rather than to whatever was in the parts bin.

Every bar is E-mark approved and tested to CISPR 25 Class 4, which matters more than it sounds: an unfiltered bar puts noise onto the vehicle bus and into the radio, and that is the complaint that comes back through the distributor rather than the one the fitter notices on the day.