invention which is similar to the embodiments of fig3 a and 3b except that the cover 30 is internally threaded and detachably fits onto corresponding threads 35 in the housing 20 so as to secure the insert 10 in place the recessed portions 5 39 in the housing 20 ensure that the insert 10 is itself recessed below the outermost circumferential surface 21 of the face of the housing 20 so that the insert 10 does not interfere with the capping operation of the device for example the position of the insert 10 is not altered upon placing the cover 30 onto the housing and locking it thereon regardless of whether that locking operation involves a small twisting motion the embodiment of fig3 a and 3b a threading operation the embodiments of fig4 a and 4b a snapping operation the embodiments of fig5 a and 5b or some other operation fig5 a and 5b illustrate yet another embodiment of the present invention which is similar to the embodiments of fig3 a and 3b except that the cover 30 is configured to create a detachable friction fit over housing 20 thus with insert 10 positioned in place in the housing 20 the cover 30 together with lens 40 is frictionally engaged to the outer surface of.