Measureless concentration with a limited object (Buddhism)

Concentration is familiar, well developed and capable of being condition for a higher jhana; however the object of concentration is unextended and therefore limited.

According to Hinayana Buddhism, concentration is considered as of one kind (monad), of two kinds (dyads), of three kinds (triads), of four kinds (tetrads) or of five kinds (pentad). In the second tetrad, this is the third concentration.