The larger Kershaw AO’s work the best. Also made by Kershaw are the beefier Zero Tolerance knives. The Zero Tolerance Models 350 and 400 are nice, but more expensive than the normal Kershaw Models. The normal Kershaw AO knives with a 3-inch blade (or around 3-inch) work beautifully. The smaller blades don’t seem to have enough blade inertia to reliably open until lock.
If you go to Youtube and do a search on the knife model you are looking at then you can usually find videos showing how it operates.
Have been lost 'window' shopping on Amazon for a half hour .. lol
Like the looks & price & comments, esp. re opening speed, of the Kershaw Volt II.
At $24 it might be irresistible (til the next one comes along ;-) . . .