BT30 ER25UM-70L,100L ER Collet Chuck Size:BT30 ER25UM-100L so you can just check

so you can just check the description of size from other brands to fix this insert

but 50 mm and 63 mm cutters are usually standard in this range

you can use any ISO inserts of RPMT1204/RDKW1204/R6 OF mostly brand into this

SOMT12T3 ASX400-080-A06R DIA 80 FACE MILLING CUTTER

EMRW 6R50-22-4T-H

BT30 ER25UM-70L,100L ER Collet Chuck Size:BT30 ER25UM-100L so you can just checkBT30 ER25UM 70L,100L ER Collet Chuck BT30 Tool Holder accepts all ER25 collets ER25 Collets range from 1 mm to 16 mm The thread inside the internal stop screwMade from alloy steel hardened to 54 56rcBalanced to G6. 3 at 12,000 rpmsConcentricity is less than . 005 micron up to 100 Length and 0. 012 up to 200 Length. All critical tool holder surfaces are precision groundCoolant through capabilityThe gauge length is 70mm,100MMThe rear thread for the pull