Like New Mamiya 12mm Extension Tube NA-401
For 645AF, 645AFD (I, II and III) and Phase One P645
$145 Shipped and Paypal'd in the US

I bought the tube new from Arlington Camera last year. It has been lightly used, indoor use only. Works like a charm, looks like new and comes with the box, caps and instructions. The NA-401 tube turns the 80mm AF lenses into excellent macro lenses. These tubes now sell for $240 new (B&H page).