Learn Farsi: مثلاً این دستگیره یک نمونه‌ی فیزیکی است. - For example, this handle is a physical sample.

masalan is an adverb meaning 'for example,' used to introduce an entire clause or sentence. In contrast, az qabil-e and nazir-e are prepositions meaning 'such as,' and must be followed directly by a noun phrase. You couldn't use them to introduce a full independent clause like 'this handle is a physical sample.'

How does the spelling of 'masalan' (مثلاً) work with that double dash at the end?

That double dash is called a 'tanvin', an Arabic marker used heavily in Farsi to turn nouns into adverbs. It is pronounced '-an'. Here, it turns the noun masal (example/proverb) into the adverb masalan (for example).

How is the word 'dastgire' (handle) constructed?

It is a compound word made of dast (hand) + gir (the present stem of gereftan, to take or catch) + the suffix -e, which often forms nouns for tools or objects. Literally, it means a 'hand-catcher'!

The translation says 'sample', but doesn't 'nemune' mean 'example'?

It means both! nemune is used for a physical 'sample' or 'specimen' (as in this sentence), but also means 'example' as an abstract concept. In fact, instead of masalan, you will often hear barāye nemune used to mean 'for example'.