Tefillin Mirror with Compass

I got 1 for each of my students, and thew are loving it!

How does someone come up with such a good combination for such a reasonable price?

If a Shul does not Daven towards Jerusalem/Har Habayis then you still Daven in the direction that the Shul Davens unless it is opposite of Jerusalem so a compass is certainly not needed.

It is often difficult or not practical to build or set up a Shul in order to Daven in the exact direction. If one is Davening outdoors and does not know in which direction is Mizrach then a compass would come in handy. The mirror is just a quick and easy way to verify the Tefillin are in their proper place.

To measure with ones nose (which is in the exact center of the face)/fingers or asking someone next to you is fine too. The reason why the mirror option is newer is possibly because some Poskim frown upon the use of a mirror (including the Satmar Rebbi and Rav Moshe) and perhaps the mini cosmetic mirror was popularized by the advertising businesses suggesting them to Sofrim to give out/sell. Others allow the use of a mirror but it should be small and should not be used to check out ones hair, pimple on the nose, etc. while checking the placement of the Tefillin. Many people do not use a mirror. The mirror. etc., should not be kept in the velvet bag with the Tefillin but rather in the plastic bag protecting the velvet bag.