Swell is a sheath that strokes the guy while he pumps. The inside shaft is loaded with nubs and more head room. Swell adds girth and length to you. Materials plus + silicone a Thermoplastic Rubber TPR, Silicone blend. Lube safe with water and silicone lubes, oil base lubes not. Dimensions length 8.25 inches, width 2 inches to 2.5 inches. Main Hole circumference 4.5 inches. Shaft hole circumference 3.5 inches. Inner shaft depth 5.5 inches. Ball hole circumference 3.5 inches. Shaft circumference 5.75 inches to 7 inches.