I have just removed a 500x500 vent and replaced it with an inverter A/C and as it's near new I thought someone may have a use for it.These often get sun damage and crack, and the sliding screens seem to wear quickly as wellMost of it is near new as I replaced the top, catches and bottom late last year.So i have everything except the plate to mount it to the roof itself.Would be ideal to refurbish your existing vent.Cost me $230 last year. asking $50.00Pick up only sorry.