Based on this product's specifications, here are some alternatives and similar models
Ink pad COLOP E/30 Colorless (model 650-00172) for self-inking devices
Summary description:
COLOP E/30 Colorless ink pad (model 650-00172) is a replacement pad designed for compatible self-inking stamp devices. The colorless pad provides neutral impressions and is intended for maintenance, protecting stamp mechanisms during storage or transport, and preventing unintended marking. Easy to install, it maintains stamp function without adding color.