From Wiki

Concise No. 300

• Type: Circular
• Size: 5 Inches / 12 cm
• Material: Plastic
• Scales:
  • Front: K A D / C CI B L
  • Back: LL₃ LL₂ D / C S T₁ T₂ ST
• HvH: 5646

With vinyl case. Front and rear disks slide independently. Slide circles set flush to body. D scale runs clockwise on each side, with indexes aligned. Thus flipping the rule gives a reciprocal on the reverse D scale. LL₂ covers e^0.1 to e, LL₃ covers e through e¹⁰. Obtained from Concise in January 2006.

Instruction Sheet, page 1
Instruction Sheet, page 2