This is set of four achromatic objective lenses for DIN-standard microscopes. Compatible with RMS-thread nosepieces, and 160mm tube-length finite-conjugate microscopes. The set includes the most common magnifications for biological applications, including: 4X, 10X, 40X, and 100X. Features & Specifications: Achromatic color correction 0.17mm cover-slip thickness DIN standard 20mm RMS-thread mounting size 160mm tube-length Contents: 4X NA 0.10 10X NA 0.25 40X NA 0.65 100X NA 1.25 oil-immersion