Any Costco Hearing Aid Center will provide them. They came in a little plastic case. Says “CONNEXX” on one side and “miniR Wax Guard 10962332” on the other.
Signia, Formerly Siemens MiniReceiver Wax Guards, 1 Pack https://www.amazon.com/dp/B0856SBXST/ref=cm_sw_r_cp_tai_fwpxFbYSSV41Q