Collet ER, according to standard DIN 6499, form B, type class 2, size ER 11. Brand Gurfer with reference ER11-2.
Also available: set of ER collets, DIN 6499 B CL2, size ER 11, Ø 1,0 - 7,0 mm per 0,5 mm, 13-piece, in plastic storage case (ref. ER11SET2).
For mounting tools with straight shank.