Rochester Precision Optics (RPO) 2.0 Mil-Spec PVS-14 Ultralight Eyepiece Assembly 5A0169 with Nocturn Industries Adjustable Diopter. **Mil-spec Eyepeice lock ring included with each eyepiece** RPO complete glass assembly is ~31% lighter than Standard RPO Ultralight eyepiece core + Nocturn assembly = 1.46 Ounces Standard Mil-Spec eyepiece = 2.11 Ounces