Based on this product's specifications, here are some alternatives and similar models
Collet Shaft Proxxon Micromot 2.35 x 44 mm (model 28 815) for rotary tools
Summary description:
Proxxon Micromot collet shaft (Ø 2.35 x 44 mm, model 28 815) is a precision-mounted shaft designed for Micromot rotary tool systems. With a 2.35 mm diameter and 44 mm length, it secures small-diameter bits and accessories for fine work such as micro-drilling, grinding and engraving. Suitable for accurate positioning and stable attachment in precision hobby, model making and light workshop tasks.