| Name and Model Number | Poper's Musical Slide Rule |
| Country of Origin | USA |
| Date of Manufacture | Est 1930- 1950 |
| Front Scales | Major keys, number of sharps, number of flats, relative minor keys, major scales – up-down, relative minor scales – up, relative minor scales- down, note transposition, chords |
| Back Scales | None |
| Scale Length | 15 cm (6 inch max) |
| Type of Rule | Slide Chart |
| Construction | Plastic |
| Area of Use | Other |
| Comment | Used for musical composing |
| Rarity | RR |
| Donor | Collection of Clay Castleberry |
| Match Number | 367 |
| 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. |