ER Collet Ultra High Precision 0.005mm / 5u run-out. These are not your blue/yellow boxed collets that are the cheapest of cheapest of collets that do not specify a precision value. A high precision collet allows for quieter machining, longer tool life and greater cut accuracy.
Available in ER11, ER16, ER20 and ER25 in common sizes 3.175mm (1/8"), 4mm, 6mm, 6.35mm (1/4"), 8mm, 10mm and 12.7mm (appropriate to ER size). Clamping range is that of nominal inner diameter size -1mm (eg. 6mm would accept 5mm to 6mm).
How to check what diameter you have
|ER-11||18 mm||11.5 mm||0.5—7 mm|
|ER-16||27.5 mm||17 mm||0.5—9 mm|
|ER-20||31.5 mm||21 mm||1—13 mm|
|ER-25||34 mm||26 mm||1—16 mm|
|ER-32||40 mm||33 mm||1—21 mm|
|ER-40||46 mm||41 mm||3—26 mm|