Hey Twitch,
That's a normal width I've typically used for many years (so it looks like). You shouldn't have a problem with the diameter of the shield seeing as how the opening is pretty wide. Mine has a smaller opening which causes me to have to manuever around a double plug sometimes.
Only concern I see is if your vacuum isn't strong enough, you may get a fair amount of plug falling thru that opening and that might make it a little messy. But that's a decent price as I normally pay about $75-$80 for a shield these days and have tried different routers up to $150 in itself.
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Rick Leong - Ten Pins Pro Shop
Tag Team Coaching - Co-Founder
"El" Presidente of the Legion