Torx Screw 2.5 mm T8 ( Pack of 100 Pcs) 12MM APMT CUTTER ER collet sizes range from

ER collet sizes range from ER8 to ER50

APKT 11T3-C16-18-150L

so you can just check the descriptions of sizes from other brands to fix this insert

BT40 Tool Holder accepts all ER11 colletsThe thread inside the internal stop screwMade from alloy steel hardened to 54 – 56rcBalanced to G6

There are many Chinese brands also making the same inserts so you can just check the description of the size from other brands to fix this insert

Torx Screw 2.5 mm T8 ( Pack of 100 Pcs) 12MM APMT CUTTER ER collet sizes range fromThe hardened Star Torx screws for milling cutters offered are screws that come with precision design and construction standards. These Torx screws are hardened to 50 55 HRC for wear resistance. These Torx screws are primarily used in indexable tools, including boring bars, insert cutters, and milling cutters. They are precision screws designed to improve the grip of carbide inserts with pockets. One packet contains 100 pieces; choose the length.