Here is one explanation of the electronics (variable resistance): https://www.powerbreathe.com/product/powerbreathe-k-series/?attribute_select-model=K1 https://

Here is one explanation of the electronics (variable resistance): https://www.powerbreathe.com/product/powerbreathe-k-series/?attribute_select-model=K1 https://www.powerbreathe.com/product/powerbreathe-k-series/?... Claim: "The K series devices all feature a unique, patented, electronically tapered flow resistive loading valve. This means the resistance is constantly monitored and tapered to match your reducing strength throughout the breath thus allowing greater flow and maximum volume rather than cutting off half way through the breath."