Detachable mezuzah case
I came a across a mezuzah case, where it slides off the rack, this is to allow easy access to have it checked without the pain of having to put new wholes in the wall. It is a special patented invention, sounds cute and smart, however this is not an adequate setting to the doorpost which halacha requires. See Yoreh Deah 189:4- that one should affix a Mezuzah with nails, (as to make it permanent). Note, that the blessing we recite is "Likboah Mezuzah"... to set a Mezuzah (scroll)- showing that it should be made on a permanent way.
It is self understood that one could not make a bracha on seting such a case either.
Now it is shown to me that this case was already mentioned in the Sefer Pischei Shearim p. 334 that it is not kosher.