Based on this product's specifications, here are some alternatives and similar models
Chimney inner sleeve WADEX 125 mm diameter model 125120130
Summary description:
Chimney inner sleeve WADEX with 125 mm nominal diameter, model 125120130. Designed as an internal lining component for chimneys and flues to improve gas flow and protect masonry from heat and combustion by-products. Suitable for retrofit or repair of existing chimney systems where a 125 mm liner is required; used with compatible connectors and sealing materials.