Lensbaby Accessory Kit Macro Lenses - Lensbaby Creative Aperture Kit with One f/4 Star, One f/4 Heart & 5 Blank Aperture Disks You can custom cut the blank disks into any aperture shape you want 0.6X wide angle converts the Lensbaby from a 50mm focal length to a 30mm focal length, while keeping the size of the Sweet Spot constant relative to the size of the photo 1.6X telephoto converts the Lensbaby from a 50mm focal length to a 80mm focal length, slightly increasing the size of the Sweet Spot of focus Both are 37mm threaded and screw into the front of the Lensbaby for ease of use