Jrb3rd

Thanks for the help...here is the specs on the two

Hello, newbie here. I've had the cluster 02 mask for years now and want to move up to a demand valve . I am looking at the Allied Healthcare/LSP demand valve and notice there is two different flow rate models. One is 40lpm and other is 160lpm...I am lost as to which model I need...could someone please help me? Thank you in advance!