LEGO Dark Stone Gray Double Ball Joint Connector with Squared Ends (61054)

LEGO Dark Stone Gray Double Ball Joint Connector with Squared Ends has been used in at least 4 LEGO sets over the past 16 years, since it was first used in 2008. You can also find this part in at least 19 other colors. It has a design ID of 61054 which can usually be found molded into the bottom of the part.