This paper focuses on the technological characteristics of Keilmesser with a lateral tranchet blow modification on the cutting edge. It examines the underlying technological production of these bifacial objects: this implies the evaluation of their working stage succession, as well as produced forms necessary for the execution of tranchet blow performance. Furthermore, it offers a techno-morphological description of these enigmatic tools. The Keilmesser with tranchet blow and corresponding blanks of tranchet blows from Grotte de la Verpillière I in Germolles (Saône-et-Loire, France) are used as case study. The collection of Keilmesser with tranchet blow and corresponding blanks of tranchet blow has been massively expanded with new fieldwork and the review of ancient assemblages. The majority of the pieces were made on blanks from local raw material. The evaluation of the underlying production concept shows that a Keilmesser with tranchet blow, regardless of the wide range of morphologies and matrix size, always consists of specific parts that are necessary for the production sequence and the assumed function. The production of these pieces follows highly specific working stages, some of which can be interchanged in sequence. However, it is always the goal to obtain a low-angled cutting edge. The performance of a tranchet blow is not only an integral part of production, but it is rather the aim of the entire production. [ABSTRACT FROM AUTHOR]