Center holes on 7" records were once a way to decifer what speed a record was cut at. 45 RPM records had large center holes and 33 1/3 RPM records had small center holes. These days people mix and match and even get creative with them.
Small center holes:
Small center holes are available for all sizes of records and all speeds and are no additional charge. They measure 1/4" in diameter.
Large Center Holes:
Large center holes are available for 7" records and measure 1.5" in diameter. Large Center holes are no additional charge.
UK Center Holes:
UK center holes were originally offered to give the ability to easilly convert a record to large hole for jukeboxes. The section around the small center hole is perforated and can be broken out to make the record large hole. Once the center is removed it can not be replaced but a regular 45 adapter can be used. UK centers for 7" records are $.05 each.