With its total length of 40 cm, this keris can be classified as a long keris ('keris panjang', often also refered to as 'keris corok'). A keris corok is thought to contain more powerful spiritual powers than a standard sized keris. For this particular reason, many people desire to have a supernatural pusaka like this.
The pamor of this keris is pretty neat indeed, for its refined details are still clearly visible. Despite the subtle corrosion of the blade, the pamor still is entirely intact. The blade is made from 'Besi Karang Kijang', which is a type of metal with a dark-blue color, similar to that of sea water ('Ronggowarsito'). It is said that, when holding a piece of Besi Karang Kijang in one's hand, one can hear a buzzing sound, like that of a bee when it emerges from its hive; and thus, such type of metal is considered very suitable for a keris. It is, however, difficult to confirm its exact origin, though based on the corrosion this obviously is an old keris ('sepuh'), which possibly originates from the Tuban Nom-noman era ('tangguh').
Tilam Upih means 'white (bed)sheet', which implies living a straight (hence 'lurus' instead of 'luk') and honest life, thereby allowing the life within one's family to be peaceful and harmonious. Next, a 'Bonang' is a traditional Javanese music ('Gamelan') instrument which consists of small gongs that are placed onto strings in a wooden frame. Generally, it is believed that a Bonang Sarenteng can offer the owner a steady and continuous form of sustenance. Thus, this type of keris basically is suitable for everyone.