just replaced my koni "inards" for koni inserts. What a mess those original parts were in. What you will recieve will be a self contained catridge (strut insert). Remove as much oil for the strut as possible, try to clean out your struts entirely. Replace with the specified amount of antifreeze (that's what my Koni instructions specified).
I've heard that this is to help with heat dissipation, but I suspect it could be to prevent possible freezing & cracking of the compoents as a result of any water being in there; it is a tight fit & any liquid present is helping to form the seal down at the bottom. That's my take on it anway.
if you have Boge oem struts, you will need to specify this to koni in order to get the right part.
it really is all straight forward once you recieve your new parts:
new front inserts on the right.
~chris