The Stone-Drew/Ashe & Jones collection currently lists the ProPlus Kit, described by the manufacturer as a Warranty Ext. Kit Pro Plus 4. It is sold as an accessory kit rather than a standalone piece of equipment.
Before ordering, confirm with the equipment documentation that this kit applies to the unit you are servicing, and read the manufacturer's terms for how the kit must be installed and registered. Keep the purchase record with the job file so the information is available if service is needed later.