Good day to you.
Below are the answers for your questions:
a) Filters come in three parts:
1. Aluminium Mesh Filter
2. 2 in 1 cold catalyst + activated carbon filter
3. anti-bacteria + hepa filter
b) Currently, We are selling all 3 piece filter at $80 promotion price.
c) It depens on the environment, The average lifespan for customer to change filter is every 1 - 1.5 years.