There are currently five types of physical caches available to find: Traditional, Multi, Wherigo, Unknown, and Letterbox. Each of these are available in six different container choices: Micro, Small, Regular, Large, Other, and Not Chosen.
In order to log this cache, you must find each type of container for each type of cache. So you must find a micro, a small, a regular, a large, an other, and a not chosen Traditional cache, then the same for Multi, Wherigo, Unknown, and Letterbox. You will need 30 different caches to qualify. This cache cannot be one of them.
Seems like Groundspeak is making it harder and harder to find Not Chosen caches. They used to come up when you searched for container type Other, but not anymore. You will have to do some digging to find Not Chosen cache sizes. There is more than one reason this is a 5 difficulty.
There is no time constraint on when you find the caches. All previous finds count.
Here are my qualifications as an example:


Project-GC Checker here:

Now for the fine print:
- Physical log MUST be signed
- Proof of qualifications must be posted with your log
- Any logs not meeting the requirements will be deleted