3/4 insoles are designed for everyday and work shoes where there isn't a removable insole. Just slip them in and usually there is no need to trim. They are designed to take up the space under the space that would normally be under your feet around your heel and arches and provide support. Although they are designed to take up minimal space they still take up a little and so might not work in a shoe that is already a snug fit.
What Superfeet say:
Superfeet have more than 45 years of experience and orthotic innovations, their insoles give you the biomechanical support your feet can depend on.
INSTANT DROP-IN COMFORT
No trimming required, for easy fit and wear in everyday, work and street shoes without a removable insole.
PATENTED ORTHOTIC DESIGN
Contoured Superfeet® shape helps stabilize and support the foot, which can help reduce stress on feet, ankles and knees.
Made for dress, casual and business shoes with a heel height of 1 inch or less.
Superfeet insoles keep their shape, delivering reliable support and comfort for up to 12 months or 500 miles, whichever comes first
Reduces friction and rubbing to help prevent blisters and hot spots
Eliminates odour-causing bacteria
SLIP RESISTANT RIDGES
Anchors the insole to keep it in place