My DME takes the attitude that if you need one part after 3 months, you need them all. I get a new tank every 6 months as well as a bag of foam filters. The part I notice that goes the fastest is the webbing on the mask. It starts to show obvious wear and stretching after about 8 weeks. My prior DME (now long out of business) never sent me any replacement parts. I do clean everything on a regular basis as well as daily wipe outs of the mask. With my DME no longer stocking the 10 foot tubing, I may need to rethink my setup in regard to the hose buddy. If the 6 foot won't work, I can buy 10s from several of the suppliers on the list.