Vapro Airtrim Racing filters 1, 2 and 3 give lower air resistance and lower humidity and heat. No 3 have the least wind resistance and warmth. If you suffer from asthma, cold-induced asthma, angina or COPD we recommend you to use the asthma filter. Asthma filter is the filter that gives the most moisture and heat, and are therefore not suited for hard training. What is the difference between all the filters? All filters gives different air resistance and heat.
Asthma filter: very tight filter that gives high humidity and heat.
Sport filter: normal filter that gives normal humidity and heat.
Racing filter: 1, 2 and 3: the racing filters gives a lower air resistance and lower humidity and heat. No 3 have the least air resistance and warmth and is suitable for those who are training very hard.