Double Door Cage Traps / Positive Sets
The question:  Are animals hard to catch?  Answer, “Easy if you know how, impossible if you don’t.”  The best part of what I am about to relate, anyone can move from novice to expert in little more than the time it takes to set a trap.
As the self proclaimed “King” of double door cage traps, I have been an advocate of using equipment that exhibits the most versatility, multipurpose traps that can be used anywhere, in any manner, set the you choose to set them.  Some manufacturers make single door cage traps as their primary device, while double door traps appear as  more of a sideline trap.  All of our cage traps were first made to be double door traps and for good reason.  Double door traps have more uses, more options.  
Along with versatile/multi-functioning traps, I am a huge promoter of bait-less “positive” trapping of all kinds whenever possible, for a host of reasons.  Positive setting relates to den trapping, entry and exit holes where animals live, either free standing in the ground or in and under structures.  Cages with two doors may also be used along structure and for dig-outs under fences.  Double door traps used with positive sets without baits or lures is the most productive way to trap, sometimes taking animals in only minutes after traps are placed.  But, this does not prevent any trap from being set with bait if desired.  It just means that bait is most often not required for success, often better without it.  
Follow the reasoning.  Why would you set a trap in the open, with nothing on your side, to take a chance on an animal being interested in your bait or lure if there was a better location only inches away capable of catching the animal minus the element of chance?  Why would you try to make an animal come to you, replacing certainty with hope when you can often easily go to the animal with a double door trap in a positive set?  Answer, you wouldn’t.  It makes far more sense to use equipment and techniques that rely on no attractants, to take an animal that merely has to move, to catch him either coming or going where he lives.
Yes, there are situations that don’t readily allow for the use of double door traps or positive and trail sets, but not as many as you think once you begin to study and understand.  There are more opportunities than you realize, faster to set and will produce better.  All of these double door traps can of course be used with baits in either single or double door mode, all options open.  We do make single door traps.