I was unaware of that, however I do know that they produce a quality good at a low price. they kept other manufacturers out of the industry for a long time simp

I was unaware of that, however I do know that they produce a quality good at a low price. they kept other manufacturers out of the industry for a long time simply by producing a quality good at such a low price it was not worth the capital outlay to get into the market for the small profit (per unit) available. now of course the chinese can make things for fractions of what it costs elsewhere so almost all alternative zip maufacturers are low quality chinese manufacturers.