This CPU has a 486 instruction set and a 386 pinout. SLC/e stands for low power (SMM: System Management Mode) version of a Cx486SLC.
Comment by Paul Hoffman (paulhoffman18[at]gmail.com): the Cx486SLC/e was packaged in a unique package named `MQUAD` developed and produced by Olin Interconnect Technologies. The package had a black-anodized lid and base that was attached to the leadframe with an adhesive seal. The characteristic sign of the package was the circular pattern in the center of the lid (as in the picture). This was actually a small anodized aluminum disk that was used to seal a vent hole in the package lid (venting was required during the cure of the adhesive seal). The MQUAD package offered superior thermal performance due to its aluminum body - but was relatively short-lived as it was a non-standard package technology.