12 New 30X Doublet Round Eye Loupe. This is a new set of 12 doublet lens loupes made of optical glass with a round swing-away chrome plated case. The shape allows them to rest comfortably in the eye socket. These have become the standard style of loupe used in the watch making industry and is excellent for any application where magnification is needed. In terms of performance, they are second to none. Each is 30X power and has a focal distance of 1/2" (13 mm). Each lens has a 21 mm diameter.