The holster must safely retain the pistol and cover the trigger guard. If it is acceptable in IDPA or USPSA then it is good for the Texas Steel ShootoutTM.
Holster must be positioned on belt as per USPSA or IDPA rules.
Magazines can be of any capacity, but can only be loaded with no more than 10 rounds after the buzzer sounds. Magazine pouches may be placed anywhere on the belt.