Columbus Invisible Insole with Internal Height Increase (3.5cm) (For Men) This invisible insole with internal height increase is specially designed for men, easily adding 3.5 cm to your height. The comfortable low-rebound material gently wraps around the heel, making boots fit better. The insole is made of high-quality latex, effectively lifting the heel to provide stable support and improve knee alignment, allowing you to walk more comfortably and freely. Note: For fabrics or surfaces that are not smooth, adhesion may be impossible; do not use.