September 10th, 2007
Work of breathing varies with CCR models. The O2ptima has the shortest breathing loop on the market and because of this we can use smaller hoses. However, with this feature comes more attention to detail. The counterlung must be mounted in the right place to take advantage of the smaller hoses. The T-piece connections and ADV must be located high on the chest just below the shoulder. If you move them any lower on the chest then WOB will increase. If you feel the WOB is too great then adjust the CL higher with the attachment straps. This is critical. Once you get the CL positioned correctly, you will find that you can breathe vertically, horizontally or upside down without a problem.