5pcs 9V Battery Connector With 2.1mm x 5.5mm DC Plug 2.1x5.5 6F22 1604A PP3 USA | eBay
SDTC Tech 5pcs T Type 9V Battery Clip Connector Positive Negative Snap Lead Wire(15cm)
batteries - Connecting copper wire to a nine volt battery - Electrical Engineering Stack Exchange
Batteries for Beginners in Electronics
5/10/20pcs 9V Battery Button Power Cable Battery Buckle Snaps Power Cable Connector DC For DIY Jack Connector|cable dc|cable 9vcable power - AliExpress