Descriptions by the Manufacturer:

L405 - "Our orthotic for medium to high arches with forefoot pain, featuring a cupped heel to cushion and stabilize the back of foot and a metatarsal pad to redistribute weight to relieve ball-of-foot discomfort."

L420 - "Designed specifically for comfort, support and weight redistribution in athletic, walking and comfort footwear.  These tri-density orthotics feature a Copper Guard top cover and a layer of Pro-Shox® for superior cushioning and shock absorption.  Copper Guard's high-tech polyester fibers wick moisture away from the foot and provide a cool, friction free surface to prevent blisters and other foot problems."

L600 - "Designed to provide maximum foot comfort and protection in casual and comfort footwear. These tri-density orthotics feature a high-tech Carbosan® top cover that cushions the foot and absorbs shock forces. This innovative material is anti-odor and anti-bacterial to help keep your feet in a healthy, clean environment. Lynco Casual Orthotics are light-weight, resilient and provide unmatched support and stability. Fits comfortably in most footwear styles."

L605  -  "Our orthotic for medium to high arches with forefoot pain, featuring a cupped heel to cushion and stabilize the back of foot and a metatarsal pad to redistribute weight to relieve ball-of-foot discomfort."

L620 - "Our orthotic for low arches to flat feet with no forefoot pain, featuring a posted heel to control over-pronation and provide balance."