Here is an image showing the pin diagram of this transistor.
Classification of hFE
The KSC2688-G transistor can have a current gain of 160 to 250. The gain of the KSC2688 will be in the range from 40 to 250, for the KSC2688-O it will be in the range from 60 to 120, for the KSC2688-R it will be in the range from 40 to 80, for the KSC2688-Y it will be in the range from 100 to 200.
SMD Version of KSC2688-G transistor
The FMMTA42 (SOT-23) and PMBTA42 (SOT-23) is the SMD version of the KSC2688-G transistor. These transistors are of the same type, have similar parameters and are designed for surface mounting.
Replacement and Equivalent for KSC2688-G transistor