What is this on this 512k?

Its in the second picture over the power button.

Looks like SCSI to me.

http://cgi.ebay.com/Macintosh-512K-Computer-M0001W_W0QQitemZ300340673161QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item45edb2fa89&_trksid=p3286.c0.m14#ht_500wt_980

Direct link to picture:

http://cgi.ebay.com/ws/eBayISAPI.dll?VISuperSize&item=300340673161

I'm not going to buy it so bid away. I may already be getting a 512k.

(That ryhmes ;D )