How to replace wooden balusters with metal ones using GT's DIY Metal Baluster Connectors (formerly Connector H connectors). Any 1/2" or 9/16" metal baluster that are HOLLOW will work.
Purchase at: www.stairpartsdepot.com
Connectors can be purchased on Amazon.com:
https://www.amazon.com/dp/B08298R3BZ/ref=cm_sw_em_r_mt_dp_yY2yFb7HJ54T0
Connectors with Shoes packages:
https://www.amazon.com/dp/B089157JPT/ref=cm_sw_em_r_mt_dp_hW2yFbH4QZX3H
You can also purchase the connectors at select Lowe's stores under the "LJ Smith" label:
https://www.lowes.com/pd/Creative-Stair-Parts-3-Pack-Matte-Black-Wrought-iron-Baluster-Shoe/1000516249