A durable, compact oxygen analyzer with a user replaceable sensor, readily available batteries (AAA), a splashproof case and a reasonable price. Its electronic circuit is easy to calibrate and uses long life sensor. The case, digital panel meter, potentiometer, on/off switch and sensor are sealed to protect the electronics inside the enclosure from harsh elements. It is splashproof. A standard in performance, price and quality for oxygen analyzers for the diving community.