AFAIK the Outdoor Edge Zip-Blade is profiled the same as that on my EKA Swingblade tripe blade. Which is good. It works very well. There was some sort of joint development between them I think.
Outdoor Edge also sell their own Swingblade, made from a different steel, Japanese AUS-8. Which is supposed to be a worthy steel. EKA use Swedish Sandvik 12C27 hardened to 57-59 HRC. I would not know whether one is better than another. Mine is standing up very well.
However the Zipblade is not made of AUS-8. Monarch's description is incorrect. Other websites describe it correctly.
As do the manufacturers themselves.
ZipBlade™
It is made from 420J2, which a little research will show is poor stuff. As I suppose is reflected in the price.
This may not matter much to you, it will probably do a good job. After all it won't be used anything like as much as your main knife. And is very well priced.
The EKA Swingblade I now regard as a mainly skinning knife, very useful for larder work, cutting the skin up the legs with the tripe blade, easing away any parts where the fur won't just peel off with the main blade (Muntjac being particularly recalcitrant and such a tough skin) etc. The main blade shape is, I now realise, not ideal for gralloching. So I now have a different fixed blade knife which is much more suited to use in the field. And being more experienced now find no need for the unzipper, I can do it all with the one knife. The swingblade is carried as my backup. And the tripe blade has come in useful a few times for cutting down the sternum on some tough old animals, where I didn't want to use my best knife, it is very sturdy and the hooked shape is perfect for that, the blunt tip also when doing a suspended "everything out" job.