| Name and Model Number | ADF Products ARC Extended Scale Semi-Circular Slide Rule |
| Country of Origin | USA, NYC |
| Date of Manufacture | c.1960 |
| Front Scales | L, S, T, & 10-M long scale in 25 semicircular sections. |
| Back Scales | NONE |
| Scale Length | Number scale is 10-m long |
| Type of Rule | Slide Rule |
| Construction | Painted aluminum with 2 transparent cursors |
| Area of Use | Generic |
| Comment | This semi-circular slide rule was designed by Andrew Frankenfield who still lives in New Jersey. He designed and sold this slide rule. The production was limited as no examples are known in circulation. |
| Rarity | RRRR |
| Donor | Collection of Ed Chamberlain |
| Match Number | 103 |
| Thumbnail (Click Picture for Details) |  |
| In conjunction with our 'donors' we assign a rarity rating to each item, based on the system devised by Herman van Herwijnen |
| (1929 - 2004), renowned Dutch collector, author, and creator of Herman's Archive, a collection of 5,000 slide rule images on CD. |
| • RR = Rare - 1 of 25 collectors has one; it may take a year to find an example in the marketplace. |
| • RRR = Very Rare - only a few known to collectors; may be several years before it comes up for sale. |
| • RRRR = Extremely Rare - a museum piece; unlikely that an example will come up for sale. |