The cushy mask.
https://www.medexsupply.com/ems-supplies-airway-management-resuscitation-masks-allied-healthcare-reusable-cuffed-mask-adult-size-4-x_pid-73649.html?pid=73649&gclid=CjwKEAjwrcC9BRC2v5rjyvSbhWASJACKkjDzS0KOQ_c3FCR6Qcy9F__9AI9hnPETzGA_rtuAEsEalRoClVbw_wcB
The dog ate mine a few months ago, and I just ordered a new one.
I wonder if you can use it with a standard bag setup, instead of the cheap plastic re-breather masks - the value of a mask like this, I suppose, depends on how much you use the O2.