The adapter is used with the Bosch templet guides. It self centers when installed; however, a check with the centering post is always a good idea. I installed mine on both my fixed base and plunge base (1617 series router). Both centered fine with no issues. The fixed base installed easily and did not interfere with the duct collection. The only downside is on the plunge base (very rare that this is used; however, I did have a specific use). The plunge base dust collector will not fit over the templet adapter correctly. Just a minor thing as (like I said) not a likely configuration.