You use them for Torx fasteners.
To turn Torx screws.
Torx type? use torx screwdriver
Torx type? use torx screwdriver
I believe that's a Torx 25
Torx screwdrivers are usually used in small electronics like computers and phones.
I assume this means: "Where can I find a torx screwdriver". Torx is a screw, with a hole looking like a six pointed star, or the star of David. You can find a Torx screwdriver in pretty much any hardware store, or well stocked super markets. They come in different sizes, so make sure you get the right size. They also come in the shape of Alan-keys, or hex-keys.
Your local auto parts store
A Torx screwdriver can be purchased through an online retailer or in store. Online retailers include Amazon, or IFixIt to name a few. In store retailers like Home Depot or Home Hardware would have a Torx screwdriver.
Rather than a screw or bolt head having a single slot to take a screwdriver, a torx screw head system uses a six-pointed star shape, and a screwdriver designed to fit.
You need a torx screwdriver....
A Torx screwdriver set can be purchased online at home hardware stores such as Home Depot as well as Tractor Supply. One may also try to search on Amazon or eBay for better deals.