Description: set of cork borers. Left to right sizes 6,7,8,9 nested, size 5, American penny for scale, sizes 4,3,2,1 nested, pusher. Used for making holes in corks for glass tubing in chemistry labs. Background is 1/4" square graph paper.
Source: self made
Photographer: Richard Frantz Jr. (I release this to public domain).
Public domainPublic domainfalsefalse
أنا، مالِك حقوق تأليف ونشر هذا العمل، أجعله في النِّطاق العامِّ، يسري هذا في أرجاء العالم كلِّه. في بعض البلدان، قد يكون هذا التَّرخيص غيرَ مُمكنٍ قانونيَّاً، في هذه الحالة: أمنح الجميع حق استخدام هذا العمل لأي غرض دون أي شرط ما لم يفرض القانون شروطًا إضافية.
This image has currency in it to indicate scale.
Using coins for scale is discouraged as it will require people unfamiliar with them to look up the dimensions or guess, both of which defeat the purpose of the object in the first place. Coins can also reinforce a geographical bias, and some coins' designs are copyrighted.
Ideally, a photograph should include a ruler with the subject (example) or an added scale marking.
SI ("metric") units are the most commonly used worldwide (see meter and centimeter).