This policy setting allows you to configure a minimum length for a Trusted Platform Module (TPM) startup PIN. This policy setting is applied when you turn on BitLocker. The startup PIN must have a minimum length of 4 digits and can have a maximum length of 20 digits. If you enable this policy setting you can require a minimum number of digits to be used when setting the startup PIN. If you disable or do not configure this policy setting users can configure a startup PIN of any length between 4 and 20 digits.