This sex toy lifts your penis and testicles upwards and pushes them forward. The penis and testicles swell more because the penis sling ensures that the blood flowing to your testicles stays there. The toy is made of liquid silicone, a unique material that feels incredibly soft and is very elastic for a perfect fit. Diameter: - Small ring: 2.5 cm inner diameter, 4 cm outer diameter - Large ring: 3 cm inner diameter, 4.3 cm outer diameter.