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".