The bases are made of a high-quality plastic that is not affected by external influences, making them suitable for outdoor use.
The bases are available for a ball of 10 or 11 mm. This is the diameter of the ball. This will fit the inserts equal to the last number of the base. So base 58-2 fits base 2.
The advantage of these bases is that, after replacing the old cap, they are only applied once. After this it is very easy to replace the insert on your own.