Reducing sleeve, modular system for providing a reducing sleeve assembly, and machining assembly

A reducing sleeve for fastening a machining tool in a tool holder is described. Said reducing sleeve comprises a reducing sleeve body, which comprises a first tool-side end and a second tool holder-side end. In addition, at least one coolant supply channel is provided in the reducing sleeve body. Furthermore, a multifunctional interface is arranged at the second end and is designed for coupling to a sealing unit and a safety unit. Additionally presented is a modular system for providing a reducing sleeve assembly, which comprises such a reducing sleeve, a sealing unit, and a safety unit. In addition, a machining assembly with a tool holder, a reducing sleeve, and a machining tool is presented.