... S3700-SI.**S3700-28TP-EI is short for S3700-28TP-EI-AC and S3700-28TP-EI-DC. As product versions are ... 24 Ethernet 10/100 ports, 2 Gig SFP, and 2 dual-purpose 10/100/1,000 or SFP, DC -48V)S3700-28TP-EI-DC ... Mainframe (24 Ethernet 10/100 ports, 2 Gig SFP, ... and 2 dual-purpose 10/100/1,000 or SFP, DC ...