Nikon PK-3 27.5mm Extension Tube * Nikon F * For: 55mm Micro f/2.8 or f/3.5
For: 55mm Micro f/2.8 or f/3.5 Lenses. Nikon PK-3 27.5mm Extension Tube. Mount: Nikon F. The PK-3 Auto Extension Tube allows a lens to focus closer than its normal set minimum focusing distance.