Breathing filter to prevent the transfer of dust particles, bacteria & viruses as small as 0.02 microns. This filter allows normal passage of air while breathing into the AltoLab unit. However, the internal filter surface should not get wet, as water droplets will block normal air flow. When this happens, let the filter dry before using again. Some people use a hot hair drier to dry out filters if they should get wet. For proper hygiene it is best not to share breathing filters with others. Breathing Filters F100Regular price: $15.00Sale price: $12.50 The swivel tube requires a special green "elastomeric" connector (see inset photo) that fits into the top of the AltoLid where the swivel tube or a breathing filter is inserted. This green connector is included with the purchase of each swivel tube along with a mouthpiece. The expandable swivel tube offers the greatest comfort and comes standard with the AltoLab PERFORMANCE and ELITE kits. Its swivel elbow moves freely allowing movement in all directions of the AltoLab stack and the tube expands and bends in any position. C103Regular price: $42.00Sale price: $32.00