Enriched Air course ( e-learning + Classroom lecture )
"Enriched air " also known as "nitrox" refers to using a breathing gas mixture with a higher oxygen content than normal air. While the oxygen content in regular air is 21%, enriched air typically ranges from 22% to 40% oxygen. This higher oxygen concentration allows divers to extend their no-decompression limits and reduce the risk of decompression sickness.
$160