Sorry, kind of off topic again but I know people here are using these

Sorry, kind of off topic again but I know people here are using these inserts. So I ordered:

Just wanted to confirm that the ID of holes I want to use them in should be 5.1mm (i.e. the A dimension on the diagram)? Or are you realy supposed to taper the hole?

I use 5.1 or 5.2 the little bit of excess plastic will get pushed out of the way by the heat. I also stick a screw in it before inserting, just in case my hole is a bit undersized. Any excess plastic in the hole will act as a thread lock, sort of like nylon insert lock nuts. Once its all cooled, remove the screw. it will end up being a very clean installation.

I usually use the upper end number just because the IDs on a print are always a bit undersize. You may want to print a couple tests to see what work best for you. You can always get the insert back by heating it a bit and quickly threading a bolt in and popping it out.