SkiffRopes uses a 4mm Selma splicing fid every day. 

The 4mm ID fid works well with 3mm and 4mm LIROS D-Pro Dyneema® SK78, Marlow D12 Dyneema and 3mm and 4mm Dynice®.

 Selma fids are made in Norway.  See more info on the Selma website.