Was the right knockout hole used in this case

This exsisting metal box that is in place on the inside of an exterior cinder block wall is 3"H x 2"W X @2-1/4"D. I had a receptacle installed in what was once a with a vacant box.However, In this box it has two knockouts top and bottom of box and one knockoout in the back middle of box. The other outlet boxes in this house are of the same size and kind all utilize one of the top or bottom knockout holes for wire access to receptacle. The 4 knockouts for top (2) and bottom(2) of box measure 5/8" and the knockout in middle back of box measures 3/4". Are these knockout holes for install options,or only to be used with specific wire size applications?(wire used in this case was 12-2) The electrician i hired to do this is good and well established ,but gave me a short quick answer which kept me wondering..hence my reason for asking the pros here.

The knockout access hole that was used with the 12-2 cable was one of the top two 5/8" with a cable clamp.

Thanks to all!

Too much information.

What you want to know is "Is it OK to use any KO in a j box?"

Answer: yes

Ko

The one in the rear should have been closer to 7/8" for use with a connector of some kind with a 1/2" pipe thread. If the others have cable clamps then they were for use with your Romex.

knockouts

Yah...laughing I went overboard on the info. Are knockouts ok to use....laughing j/k. Thanks for the replys 220/21 & hj.

ko

Knockouts are okay to use, IF the proper connector is used in them, if needed.