Just got this notice from Hollis and am passing it along:
HOLLIS DIAPHRAGM-STYLE REGULATORS PURCHASED OR SERVICED BETWEEN OCTOBER 1, 2017 – MAY 25, 2018
There exists a possibility for the Hollis diaphragm style regulators sold or serviced between October 1, 2017 and May 25, 2018 with a new HP Poppet to significantly restrict airflow at low tank pressures (below 500 psi), posing a drowning hazard to consumers. Any regulator with the new HP Poppet must be fitted with the new style.
It is of the utmost importance that if you have a regulator model affected by this quality alert it be serviced and the pin replaced as soon as possible.
While no incidents have occurred, the possibility of an incident does exist. We strongly recommend that consumers take all necessary precautions when dealing with life support equipment.