This is the Aqua Lung SLT Seal Lock Technology Neoprene Neck Seal Features: Neck seal can be installed within minutes Neoprene material provides exceptional comfort Glide skin folds in for a watertight seal For use with the SLT system For those who prefer neoprene, the Sure Lock Technology (SLT) Neoprene Neck Seal provides exceptional comfort, easy installation and a glide skin that folds in for a watertight seal. Comfort has never been so quick!