yep, that oxygen sensor tool/ socket can be found @ any auto parts slinger...
the cutout is for the wire so you won't pinch it while you're taking it out.
sure, you can use a wrench, but some applications, like our cars have limited clearance & using this tool simplifies the job. adding a 1/2 drive breaker bar on it would help take it off it is tight on there... buy a can of PB blaster penetrant oil just in case.
another thing, may be excessive, put a little more anti-seize on the threads soo it'll be easier to take out in the future.
here's a pic of ithttp://
www.harborfreight.com/c...36669