This is a rare Albert Nestler early Mannheim slide rule no.9 with mahogany body, plastic scales and plastic curser with three hairlines. The rule with scales: A [B, C / S, L, T] D. The back with 29.4 cm rule and 11-½ inches rule. Below the slide, and imprinted in the wood is No.9 Albert Nestler A-G. Lahr (Baden). This model is dated to the mid 1920s. The Albert Nestler Company was established in 1878. It became a public company in 1922 (A.G) and limited company in 1968. The case is a black two-part hardboard inscribed, Albert Nestler AG No.9.