A flag that creeps up the stick and spins is the most common complaint about pin flags, and it is a fitting problem rather than a manufacturing fault.

The tube is too wide

If the sewn tube has more internal diameter than the stick, there is nothing to hold the flag down. Wind lifts it, and it settles higher and rotates.

The fix is to specify the tube against a measured stick, not against a standard.

Not every flagstick is the same

Sticks vary by manufacturer and by era, and most courses are running more than one generation at once.

That is why a set that fits perfectly on the front nine can misbehave on the back.

Practice pins are different again

Practice and short-game pins are frequently a different diameter from course flagsticks.

A set specified for the course can be unusable on the practice green, so measure both before ordering either.

What to do about the sticks you already own

Measure one, write it down, and give the number to your supplier once.

It is the single most useful piece of information a course can keep on file, and almost nobody has it written down anywhere.