5320 Series switches can stack with themselves and 5420 Series switches using SummitStack-V40 stacking (10G link running at HG). 5320 Series can also be stacked with 5520 Series switches using Alternate stacking (10Gb link running at HG). The 5320 Series extended temperature (XT) switches, models 5320-24T-4X-XT and 5320-24T-24S-4XE-XT, can only stack with themselves using SummitStack-V40 stacking.