Nikon K2, K3, K4 and K5 Extension Rings are non-meter coupled extensions that offer a generous range of extension. Rings fit between the camera body and lens and accepts any Nikkor lens, 20mm to 300mm. Individually, they offer 5.0 (K2), 5.8mm (K3), 10mm (K4) and 20mm (K5) extension. Together they offer a 40.8mm extension. Each extension may not be used individually. They have to be used in combination with another extension tube. The extension tube set does not preserve automatic diaphragm.