Mars-Tech ER Nut ER40 UM Type Nut pack of 1 2fluteballnosecutter2.5mm ER16M Wrench works on this

ER16M Wrench works on this collet nut

Cylindrical Shank / Straight Shank Collet chuck also called Baby collet chuck because of small size and same chuck which comes in BT40 or big tapers

BAP 400R 160-40-8T- Suitable Holder FMA40

100L ER Collet Chuck

Mars-Tech ER Nut ER40 UM Type Nut pack of 1 2fluteballnosecutter2.5mm ER16M Wrench works on thisHolds all ER40 collets from 3 mm to 26 mmMade from alloy steel hardened to 54 56rcPrecision ground ID thread and taperHas an ID thread of M50*1. 5POutside diameter is 63 MMSUITABLE SPANNER IS ER40UM AND ER40 C TYPE key to tightening The internal cam removes the collet when unscrewedMARSTECH CODE IS ER40UM TYPE NUT