Okay basicly there were Circassians slave warriors in Safavid Empire but they were not as numerous as in Mamluks, as I guest their equipment is local of the country they are serving in.

I think:
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You should just search for Ghulams they were totaly different than Circassians in
homeland.
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They are from Circassian slave caste, but are also carefully chosen from a group that has already lived very hard lives.

Because of the Martial family relations they more easily accept separation and adapt to their new environment. Which means when they arrived they quickly became loyal soldiers.

They must have been elite units (no nationalism is intended: )

Russia: Circassian Cossack cavalry similiar to Polish system.

Turkey: Special Circassian Cavalry units (my great grandfather was one :D) +Circassian heavy Cavalry from Mamluk earlier.

Poland : Cossack Cavalry divisions made of Circassians and lead by Circassian Princes.
Egypt: Circassian Mamluks
...

Though there were also rare cases when they were cheap irregular fighting men: Russo-Turkish war of 1877-78 but its quite irrelevant.