Compressed air filter inserts are manufactured with an aluminum or plastic attachment to separate mechanical impurities of oil and water from the compressed air to the required level. The DD type filter insert contains a microfilter to remove dirt up to 0.1 micrometers, residual oil up to 0.5 mg/m3. The PD type filter cartridge contains sub-microfilters to remove dirt up to 0.01 micrometers, residual oil up to 0.01 mg/m3. The QD type filter insert contains an activated carbon filter to remove impurities smaller than 0.01 micrometers, to remove odors and separate oil vapors up to 0.005 mg/m3.