The paper size is 215.9 mm in width and 279.4 mm in height which equates to 8.5 ins by 11 ins.
The size of one label is 102 mm in width by 49 mm in height which equates to the dot matrix labels supplied by Avery OML103 reorder code 126.
All of these items should be easily available from your local stationers:
e.g. Staples, Viking etc.