This is the only spindle I've ever seen that has a hole in it. I'll take the liberty of calling it a 'Keyhole' Spindle. This spindle is free standing and does not touch the side.
The float measures 2 1/2 inches in diameter.
The seal also has a circular stamp that is about 1/4 inch wide with a dimple impressed into the center. This may be WP #252 or an undocumented mark.
I think this is a fantastic spindle float.