CPR masks are a must when performing CPR or rescue breathing as they help prevent transmission of harmful bacteria. Mars Wellness, a name synonymous with quality resuscitation supplies, manufactures these CPR key chains. Branded with the Mars Wellness, these 2" x 2" ultra-compact, easy to use CPR Mask feature the CPR face shields with one-way valves (not just filters like some brands) that prevent cross contamination. These are great as all around CPR masks, as one size fits children to adults. Remember to put one of these CPR keychain masks in your 72 hour and first aid kits.