PwnCNC has a variety of collet nuts available depending on your needs. Our spindle motors will use either ER11A or ER20A nuts.
Note: The ER11M nuts are not compatible with PwnCNC Spindles. A small batch of them were purchased as a way to verify and unfortunately they won't work. They are high quality parts i'd like to sell to someone who can use them.
If you're looking for collets... checkout our ER11, ER11 High Precision, or ER20 collet options.