The entire idea behind having a TR drive is for it not to be part of a regular standard. You can go on line to Textron and get the Torx TR standards, but they are the ones who control them not an independent organization. The most common TR drives are the post hex and post Torx, you can pick oyour choice. Make sure that you have a source for the drive bits for whatever system you choose. Having to have special bits made up costs a bloody fortune.