I thought the new wheel collars with o-rings to seal them would be a good thing to have for a woods bike. I ordered a "set" for $50. What I got was two front wheel collars, 4 o-rings and bearings and seals. Tried calling PW, but got no help. Nowhere does the website say that the set is front only. My bike nis new, so the bearings and seals were not needed either. Buyer beware, I suppose.