These bulbs are extra robust and have extra support for the filaments inside. Harley have specified them for years as they resist vibration damage. (Within reason).
The only problem is that they are not widely available, so I bought this one as a spare for my emergency kit.
it's bright and alright, in fact its fandabidozy! What a bulb since buying these 2 bulbs I can run faster, beat the local bully in a fight, pull beautiful women. The bulbs are bulbs of great satisfaction.