The most professional look and most reliable option for keeping your umpire or referee shirt in place is the Hero’s Pride Footloop Style Shirt Holder with Locking Clamps.
These shirt stays and sock garters are perfect for keeping your shirt or socks at a comfortable place. These would work well with just about any outfit and would be perfect for a uniform or military attire. These are one size fits most and adjustable up to 30 inches.
The set comes with 2 adjustable split Y style shirt stays with locking clamps per strap.