The 3pc jewelers loupes set includes one 10X 21mm chrome loupe, one 30X 21mm chrome loupe and one 10X&20X dual butterfly loupe. * The 10X power loupe has a focal distance of 1" (26mm), the lens size is 21 mm diameter * The 30X power loupe has a focal distance of 1/2" (13 mm). The lens size is 21 mm diameter, it also include a small loop to attach to a neck chain or key chain. * The dual butterfly loupe has 10X power lens with 18 millimeters and 20X power lens with 12 millimeters, the strong magnifications with a mid distance of 1/2" (13 mm) as well. * They are all made of optical glass and protected when not in use by the swing-out chrome plated metal cover, it"s perfect for pawn shops, antique stores and jewelry shops. Both loupes come in a protective plastic case.