Find Your Optic Spacer Size
Your spacer size depends on the outside diameter of your eyepiece. Measure it, then find the matching range below.
| Spacer | Eyepiece outside diameter | Inches |
|---|---|---|
| Alpha | 39.4 to 41.7 mm | 1.55 to 1.64 in |
| Bravo | 41.9 to 44.2 mm | 1.65 to 1.74 in |
| Charlie | 44.5 to 46.7 mm | 1.75 to 1.84 in |
| Delta | 47.0 to 49.3 mm | 1.85 to 1.94 in |
| Echo | 49.5 to 51.8 mm | 1.95 to 2.04 in |
| Foxtrot | 52.1 to 54.4 mm | 2.05 to 2.14 in |
| Gulf | 54.6 to 56.9 mm | 2.15 to 2.24 in |
| Hotel | 57.2 to 59.4 mm | 2.25 to 2.34 in |
Maven optics
- Maven S.1.2: Gulf
- Maven C.1: Charlie with the full kit. The Mini also fits.
- Maven C.4: Bravo. The Mini does not fit.
- Maven CM.1: works with the Mini.
- Maven B.7 and C.2: too small, do not fit.
Not sure?
Measure the outside diameter of the eyepiece with a ruler or calipers. If it falls between two ranges, or your optic is not listed, get in touch and we will check it for you.
Binoculars: the On Glass Mini fits eyepieces from 39.4 to 45.7 mm. It fits most binoculars but not all, so check with us if you are unsure about yours.