This is a one year type. The 1842 Keping is a very rare coin and is usually found in "very good" to "fine" condition (in other words, very worn). Many modern counterfeits exist, both in copper and in brass.
The coin was authorised by the Rajah, James Brooke, in 1842. According to Remick's "Catalogue of British Commonwealth Coins 1649 - 1971", these coins were minted at "a private mint in Birmingham" which was not the Heaton and Sons Mint.
Some were made in copper and some in brass. Most coins were copper.
In older sources, the name of the denomination may be spelled as "kapang" or "kepang".
||Total Mintage||unknown, Rarity: R2 (Very Rare)
The obverse bears the image of a badger (or "brock") which was the crest of the Brooke Arms, turned to left; the initials J · B and the date SEPT 24 1841 (when James Brook was granted the title Rajah of Sarawak, though the official declaration to that effect only came on 18 August 1842).
The reverse was struck from an old and worn out die bearing the value و / ١ and denomination سات کڤڠ "Satu Keping" in Malay written in Jawi script (translation: one keping) and the (wrong) date ۱۲۴۷ in Arabic numerals (1247 AH =1831 CE).
This die had been used earlier in the striking of Singapore merchant tokens and was re-used for the striking of this coin.
||سات کڤڠ ۱۲۴۷
References to additional information:
[Book] Saran, Singh. The Encyclopaedia of the Coins of Malaysia, Singapore and Brunei, 1400-1967. Kuala Lumpur, Malaysia: Malaysia Numismatic Society, 1986. pp 352 and 359.