I don't know if it's where I got them from or not.I have poor vision or and if they don't get them exactly centered to your central focus they don't work as well. I'm 61 and probably need trifocals. I don't use any bi focal in my shooting glasses.
Got mine from Tom at Morgan at the PA State Shoot and love them! They really provide crisp sharp views. Great for cloudy or low light conditions. They brighten things up too much for me in bright conditions though so I use dark purple then.