Ancient Coin Review 93 : Sultan Zainal Abidin III Terengganu Pitis / Keping Coin dated 1310AH ( 1892 CE)

This is a rare pitis coin from Sultan Zainal Abidin III era. He became the ruler of Terengganu from 1881 - 1918 CE.
This is a coin from his era value at 10 Keping dated 1310AH which is equivalent to 1892 CE. From Saran's Catalog as well as Dr Ibrahim's, this coin is type SS15 however there is a slight different in the shape of the ک "kaf" where it is more flat than in Saran's. In addition to that the beginning of the س "sin" started with an elongated vertical stroke whereas its a short stroke in Saran's. It was also not captured in Bank Negara Malaysia, Terengganu Currency Heritage Catalog. Could this coin be rare?

The Arabic calligraphy used on this coin definitely a Thuluth type due to angular shape of the script. Dechipering from the script above, the inscriptions on the obverse is in Arabic whereas the reverse is in Malay :
Obverse :   ضرب في ترقانو ٠ ١ ٣ ١
                 Struck in Terengganu 1310 AH
Reverse : سفوله کفيڠ ٠ ١
                 Sepuluh Keping 10

Compare with my other Terengganu Coin from previous Sultan
Terengganu SS11
Terengganu SS33
Terengganu Unlisted

Terengganu was an important trading centre in the 13th Century. Later it became a vassal state of the Majapahit Empire of Java. By the end of the 14th Century, a Muslim community is known to have flourished in Terengganu. Subsequently, it became a tributary state of the Malacca Empire in the 15th Century.After the fall of Malacca Empire, Terengganu was claimed by the Johor Empire as part of the territories inherited from the former Malacca Empire.In the 17th Century, Johor ruler's brother was proclaimed as the first ruler of Terengganu. ( from Saran Singh's)

 
Coin Spec :



Obverse :   ضرب في ترقانو ٠ ١ ٣ ١
                 Struck in Terengganu 1310 AH
Reverse : سفوله کفيڠ ٠ ١
                 Sepuluh Keping 10
Weight : 5.60gm
Dim : 27mm
Rarity : Different Variety from the catalog
Denom : Pitis
Material : Tin
Reference : SS15 but it is different variety than the one in catalog