Used to join cable together to gain additional length.. 625″ x 3″. Also called Straights. Part number F3 and AF3. Available in Copper and Aluminum.
Crimp connecters are fine and inexpensive and should only be used where you can easily monitor them periodically for tightness. Always use bolt tension connectors on concealed systems so there is never a chance of a connection letting loose and not knowing it. Connections must be able to withstand a 200 pound pull test. This is difficult to achieve with crimp style connecters.