Other Blade Holes - Opening Systems
Other Thumb Holes/Slots Info
Since the Round Hole is a Spyderco trademark, other knife companies choosing to use a similar style of hole-based opener usually either ask for permission to use the round hole from Spyderco, or create a different shape of hole. Even Spyderco's own budget line of knives, Byrd, has a variation of the round hole in the shape of a teardrop.
Some examples of thumb holes are the Strider SnG and SmF with their capsule shaped blade hole openers, some models of the Benchmade Pika and AFCK with the oval shaped holes, Peter Atwood's hexagonal hole opener on his customs, and many more from companies like Kabar and Boker among others.