The Darlington transistor is a compound structure consisting of two bipolar transistors connected in such a way that the current amplified by the first transistor is amplified further by the second one. This configuration gives a much higher common-emitter current gain than each transistor taken separately and take less space than two individual transistors because they can use a shared collector. 
Microsemi's integrated Darlington transistors come packaged singly as an array of devices (eight or seven) in an IC.
Packaging options:
J: DIP, 16/18-pin, Ceramic, -55oC to 125oC
L: 20-pin, Ceramic Leadless Chip Carrier, -55oC to 125oC
F: 16-pin, Ceramic Flat Pack, -55oC to 125oC
N: DIP, 16/18-pin, Plastic, 0oC to 70oC, ROHS-compliant
DW: DIP wide body, 16/18-pin, Plastic, 0oC to 70oC, ROHS-compliant2

The 883B and DESC suffixes indicate compliance with the relevant military/space standard.

Looking for individual (non-array) Darlington transistors? Click here.