Alyan anahtarı tork anahtarından daha küçük.

Alyan anahtarı is a two-word noun phrase meaning Allen key / Allen wrench / hex key.

It is made of:

• Alyan = Allen / hex
• anahtarı = key / wrench, in a compound form

So the whole phrase works like a fixed tool name, not just any random combination of words.

This is because Turkish often forms noun compounds with a special ending on the second noun.

Pattern:

• X + noun-(s)ı/(s)i/(s)u/(s)ü

So:

• anahtar = key, wrench
• Alyan anahtarı = Allen key
• tork anahtarı = torque wrench

That -ı here is not the accusative case. It is the 3rd person possessive form used in many Turkish noun compounds.

You can think of it as a normal Turkish way to build expressions like:

• araba kapısı = car door
• mutfak masası = kitchen table
• tork anahtarı = torque wrench

Because Turkish marks than by putting the compared item into the ablative case.

So:

• tork anahtarı = torque wrench
• tork anahtarından = than the torque wrench

Breakdown:

• anahtar = wrench/key
• -ı = compound ending
• -n- = buffer consonant
• -dan = ablative ending, here meaning from / than

So:

• tork anahtarından daha küçük = smaller than the torque wrench

That -n- is a buffer consonant.

When a noun already has a possessive ending like -ı and then another suffix is added, Turkish often inserts -n- to make pronunciation and structure work smoothly.

So:

• anahtarı
  • -dan
• becomes anahtarından

This is very common:

• araba kapısı → araba kapısından
• evin kapısı → evin kapısından

Turkish does not use a separate word exactly like English than here.

Instead, it uses:

• the thing being compared in the ablative case: -(d)an / -(d)en
• plus the word daha before the adjective

So:

• tork anahtarından daha küçük literally works like:
• from the torque wrench more small

Natural English:

• smaller than the torque wrench

küçük means small.

daha küçük means smaller.

In Turkish, comparatives are usually formed with:

• daha + adjective

Examples:

• daha büyük = bigger
• daha uzun = longer / taller
• daha pahalı = more expensive
• daha küçük = smaller

So Turkish does not change the adjective itself the way English changes small to smaller. It usually just adds daha.

Because in Turkish, in simple present-tense sentences with nouns or adjectives, the verb to be is often omitted.

So:

• Alyan anahtarı küçük. = The Allen key is small.
• Alyan anahtarı tork anahtarından daha küçük. = The Allen key is smaller than the torque wrench.

This is completely normal Turkish. The meaning of is is understood automatically.

The subject is Alyan anahtarı.

So the sentence structure is:

• Alyan anahtarı = subject
• tork anahtarından = than the torque wrench
• daha küçük = smaller

Whole meaning:

• The Allen key is smaller than the torque wrench.

Yes, Turkish word order is flexible, although some versions sound more neutral than others.

The neutral order here is:

• Alyan anahtarı tork anahtarından daha küçük.

You might also see:

• Tork anahtarından daha küçük alyan anahtarı.
  but that would usually need a special context and does not sound like the plainest sentence on its own.

For learners, the safest pattern is:

• Subject + comparison phrase + daha + adjective

In this sentence, yes, the most natural meaning is physically smaller.

But küçük can also mean:

• young / younger
• little
• small in importance or amount

Context decides the meaning. With tool names like Alyan anahtarı and tork anahtarı, physical size is the obvious interpretation.

Turkish does not have articles like English a/an/the.

So:

• Alyan anahtarı can mean an Allen key, the Allen key, or Allen key depending on context.
• tork anahtarı can mean a torque wrench or the torque wrench depending on context.

In this sentence, English naturally uses the:

• The Allen key is smaller than the torque wrench.

But Turkish does not need a separate word for that.

Yes, Alyan is the usual Turkish term for an Allen key / hex key.

It comes from the brand name Allen, but in Turkish it has become a regular tool name. So Alyan anahtarı is a standard expression.

Yes. This is a very useful pattern:

• X, Y-den/dan daha + adjective

Examples:

• Bu kutu o kutudan daha büyük. = This box is bigger than that box.
• Ankara İstanbul'dan daha küçük. = Ankara is smaller than Istanbul.
• Bu bıçak ötekinden daha keskin. = This knife is sharper than the other one.

So your sentence follows a very common Turkish comparison structure.