Floor Springs
Floor Springs, whilst more expensive than face-fixed overhead closers, or concealed overhead closers, are the first choice for heavily used commercial timber doors, being much more robust and longer lasting than face fixed closers.
Mounted in the floor for unobtrusive door control, these closers are available for most applications and are particularly suited to heavy doors.
The Floor Springs pictured below are Ryobi 100 and 200 Series.