This office chair is in good shape, but it certainly isn't perfect. It functions well and has upgraded roller-blade style wheels, however here are the issues:
Issue #1) The cylinder drum mechanism is failing internally, the bearing fell apart and I recommend replacing it even though it does function fine as is. I put the current drum+strut back together again, but I recommend replacing it and the part will cost roughly $50 and I will replace be happy to replace this part for you for an additional $20 in labor if you'd like (I'm a good mechanic) which would bring the price up to $350 for the whole chair.
Issue #2) The left arm-rest is a little wobbly / loose.
Other than those two things the chair functions perfectly and will work perfectly for office use. The mesh has no tears in it, the rubber back lumbar support is relatively new and we have owned this chair for 16 years! It says "C2" on the bottom and it looks like a medium size. I think it's approximately 25 years old, but it's in great shape overall, the roller wheels make it very slidey!