In house we stock and use the Becton Dickinson K2 EDTA tubes for our CBC's. Some of our reference lab accounts send us the K3 tubes which they may have gotten by using another reference lab in the past or if they buy their own tubes. We notice no difference in the number of clotted specimens, MCV changes or specimen integrerity with either type of EDTA and really have no preference. Both seem to work equally well. Concensus seems to be choose the EDTA tubes that are most cost effective for you.
We run our specimens on the Sysmex XE-2100.
LR