Based on this product's specifications, here are some alternatives and similar models
Terminal ferrules Rittal AS 4050.781, copper/polypropylene, 4.2 mm dia, 18 mm length, pack of 500
Summary description:
Rittal AS 4050.781 are insulated terminal ferrules with a copper tube and polypropylene (PP) insulation. Each ferrule has a 4.2 mm outer diameter and 18 mm length, suitable for reliable conductor termination and improved crimp connections. Supplied in a pack of 500, these ferrules are intended for electrical wiring, control cabinets and panel assembly tasks.