The back of the slide-rule is marked with PATENTS APPLIED FOR on the left side and PICKETT & ECKEL, INC. CHICAGO 3. ILL U.S.A 300 on the right side. The back is marked with LL1, LL2, DF/M, CF/M, TH, SH, L, CI, C, D, LL3, AND LL4 scales.

The slide-rule also includes a leather case stamped with PICKETT and CALIFORNIA SADDLE LEATHER.

This slide-rule belonged to Walter Stewart and is marked with his name on the front of the instrument and hand-written inside the leather case. It was acquired from his estate ca. 2016 and the date of manufacture (ca. 1959) was derived from his personal history and the date range available for the instrument.

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