Below are the specifications for the Weaver J4 as listed in a Weaver 1956 advertisement pamphlet about the J2.5 and J4.

Magnification: 4X

Field of View: 26ft

Tube Diameter: 0.750 inches

Eyepiece Diameter: 1.010 inches

Objective Diameter: 1.010 inches

Eye Relief: 3-5 inches

Length: 12 inches

Weight: 6.5 ounces

Adjustments: 1/2 MOA click

Crosshair Options: Crosshair, Post and Crosshair, Range-Finder, Dot (Range-Finder and Dot crosshairs available at an extra cost)

Original MSRP: $27.50 (1956)

Inflation-Adjusted MSRP (2026 Dollars): $325.00

Notable Features: Achromatic lenses