Rochester Precision Optics (RPO) 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 Carson Industries RPO Ultralight eyepiece core + Nocturn assembly = 1.46 Ounces Carson Industries eyepiece = 2.11 Ounces