CAT tooling is according to ANSI B5.50 standard. It mainly includes CAT30, CAT40, CAT50 holders, and CAT40 Tool Holders are usually more widely used than CAT30 and CAT50.

CAT tooling is also called V-Flange Tooling or CAT-V taper tool holders. CAT Tool Holders are with both inch and metric sized tools, but mostly are with inch sizes for US and Canada market, and metric sizes for other markets. But you can also find metric size items in American market.

CAT tool holders are similar to BT, DIN69871 tool holders. The difference between them is the flange style, thickness, and the thread for the pull stud is with different size. CAT Tooling uses inch size thread pull stud (retention knob). 

There are also the same kinds of tool holder categories as BT ones, please see below:

ER Collet Chucks,

OZ Collet Chuck,

SK Collet Chuck,

Power Milling Chucks,

End Mill Holders,

Face Mill Tool Holders,

Combi Shell Mill Holders,

Morse Taper Tool Holders,

Drill Chuck,

APU Drill Chuck Holder,

Tapping Chucks,

Shrink Fit Tool Holders,

Boring Shank Tool Holder,

Boring Bar Blank,

Etc.

CAT V Flange ER Collet Chuck is the most widely used item among them, as it is can be used for drilling, milling, boring, tapping, grinding and engraving operation. It is assembled with collet and nut, threaded to the pull studs. Bright-tools CAT40 collet chucks is with high runout 3 micons, and balanced to G6.3/15000 RPM or G2.5/25000 RPM. In this way, it can adapt many working tasks.

Related reading: DIN69871 SK Tool Holders ISO10 Tool Holder