1) mask, which they are working out;
2) filtering - Soda Lime dust down to 1 micron particle sizes has been proven to pass into breathing tubes of ReBreathers used for diving, which is why I'm using bacterial/viral filters on mine to ensure no contaminants can pass;
3) the breathing bag is exposed and could be pressed/pushed upon to varying degrees if their device is somehow positioned poorly during use, which can constrict air flow. My final version fully guards dual, smaller, breathing bags inside that cannot be damaged or pressed upon;
4) material used in making their breathing bag - mine are non-latex, medical grade to ensure no allergic reactions occur causing respiratory distress issues;
5) they are using three breathing tubes, which is not only unnecessary but also holds too much tidal volume (each breath) versus having breaths reside more fully around the Soda Lime granules in a maximum time/volume fashion - mine has two breathing tubes that are adjustable for comfort/position while minimizing air volume;
6) redundancy .... my version also has two canisters, but the size of each breathing bag and soda lime canister provides 100 % redundancy for up to 0.5L of tidal volume if one canister fails. I am going to post pictures of all internal components, the assembled device, and test results within +/- 1week. All components can be purchased on eBay and/or other online sources.