- Should you be surprised by a downpour while running, the bag on the upper arm is already prepared. Be it a drizzle or a rain shower – thanks to the hermetic closure technology, the smartphone is 100% protected against water and even the finest dust. The HERMETIC armband is made of skin-friendly, elastic material and follows every movement. And thanks to the special film, the smartphone remains touch-enabled. With the included belt extension, the lengthening for larger sizes can be accommodated quickly and conveniently.