2-way or 1-way for a main zip?

[TLW '90]

I love 2 way zippers, on my Old Taylor's CMPD I unzip from the bottom up when in a vehicle.

 

[Bfd70]

2 way all day

 

[zebedee]

Only have a two-way zipper on one jacket. It’s useful for keeping the jacket mostly fastened while sitting down or if you’re carrying any sorts of heavier canvas messenger-style bags full of things that would otherwise drag the lower part of the jacket across the body. I don’t think it was designed for the second instance, but I found that it works well if I’m carting lots of stuff around.