Made of eco-friendly silicone rubber and ABS + PC material, and with rubber paint surface process. Football grain design has anti-skid protecting effect.Water resistant design ensures the device functions smoothly when it's raining; Shock-proof feature ensures the device work properly even it crashes or drops. With the free hook included, you may hang it on your backpack for long flights, road trips, hiking, camping, or such, handy to carry and charge by solar.