I ordered replacement filters for my Oxygen Concentrator and then realized I ordered the wrong type. I sent an e-mail and their Customer Service department responded the next day. After sending a picture of my filter they sent the correct ones. My thanks and complements

Shipping was quick, packaging good, setup was easy.
I used a forensic analyzer to check the O2 output initially and at 1 and 2 weeks.
Although advertised at 90% @ 2L the actual O2 % varied between 97% and 98%!
VERY IMPRESSIVE!!!