Just curious, but when did ventilated points come out?

I notice new, foreign-made replacements sold for my '55 have the vent holes, but the high quality, US-made NOS ones I sometimes get do not. Are the vents enough of an improvement to risk poorer quality control? You would think the missing metal would SHORTEN point life, especially in a positive ground system, where points last longer anyway.



Also, does anyone know if converting to dual points, can you safely increase dwell time using the stock coil without shortening it's life? What's the limit?

6 VOLTS/POS. GRD. NW INDIANA