Not rust‑proof. Standard ER‑11 collets are usually carbon/alloy steel and can corrode with water—use stainless or plated collets for water use. ER‑11 "1/4″" nominal collet is made to hold 1/4″ (6.35 mm); it only accommodates a very small undersize (use the exact size collet or a dedicated sleeve for larger variation). Title (≤115 chars): Are ER‑11 collets rust‑resistant and what is the clamping range of an ER‑11 1/4" collet? View answer
