Based on this product's specifications, here are some alternatives and similar models
Copper End Cap Conex 18 mm for Pipe Sealing — 5301018000000
Summary description:
Conex copper end cap, 18 mm diameter, designed to close and seal the end of copper pipes. Manufactured by Conex, this solid copper fitting provides a corrosion-resistant termination suitable for plumbing, heating and gas installations where an 18 mm copper pipe must be sealed. Use for temporary or permanent pipe closures and system testing.