The camouflage against radar detection was mainly meant for the snorkel. As material for the Ringschwimmer-Schnorchelkopf two half shells from layer sump were glued on. Because of delivery difficulties also a lining from wood slats was used. The layer sump consisted of conductive layers of halfpermeable paper and dielectric supporting layers. The water and pressure strength were ensured by a special plastic called "Zelligelit". There were seven layers with a total thickness of approximately seven centimeters. The hull and tower were also occasionally covered. For this purpose a black, rubber-like material was used "Alberich". It served however only for the camouflage against ASDIC, not against radar.