Made specifically for this 10 collet set with 4.15mm in outer diameter https://www.aliexpress.com/item/1005007172133278.html 

Update: Previously I mentioned I bought them for the ArgoFile Artima AT. Unfortunately that didn't work so well, as I realized the Artima's collets are 4.25mm OD, and while these 4.15mm OD collets seem to fit, the bits end up rotating notably off-center.

Note that these collets are 4.15mm in diameter. Note that despite their similar appearance these collets are not compatible with Dremel, which uses 4.3mm collets. Dremel bits will NOT fit in this holder.