The hole size in Diameter should be 5/16" on Bottom rail.
The lift cord threaded through the button secures itself within. This button can hold a maximum string diameter of 2.4mm.
Package of 10pcs Bottom rail cord cover button plugs
Semitransparent White color Plastic
The plug is for use when closing the hole at the bottom of the wood, faux wood, or mini blind. Closing the hole prevents string from exposing during regular shade operation. In addition, the top diameter of the plug measures 5/8 of an inch.