Stackable 12 SFP module slots, 1 network module slot, 350 W power supply. WS-C3850-24S-S. IP Base. Stackable 24 SFP module slots, 1 network module slot, 350 W power supply. WS-C3850-12XS-S. IP Base. Catalyst 3850 12-port SFP+ transceiver, 1 network module slot, support for up to 10 G SFP+, 350 W power supply.