The same screw eyes that came with your stand. Stainless steel is the safest and toughest metal for birds. Small is used for small and extra-small stands, medium is used for medium and large stands, and large is used for extra-large stands.
For Small, pre-drill a hole with a 3/32" drill bit.
For Medium, pre-drill a hole with a 7/64" drill bit.
For Large, pre-drill a hole with a 1/8" drill bit. Screw Eye Driver does not work with large screw eyes.
We sell these drill bits and a screw eye driver here: https://bemorebirds.com/products/drill-bits-drivers-for-screw-eyes