I am unable to test, so selling as "for parts/not working". Looks brand new, so believe it will work. HPE Aruba Networking 3810M 4‑port Stacking Module Differentiator4-port module to allow stacking of 3810M switches Weight0.26 kg (0.58 lb) Dimensions14.86 x 8.59 x 2.62 cm (5.85 x 3.38 x 1.03 in)
eBay