Southwire 65179640 SPL4/0-6AD Dual Rated, 1PK Splicer, Grey

Received it quickly at a good price

My battery cables are now twice longer than beforehand

Not much to say - does what it's designed to do.

Good item at good price

Used 3 of these to connect 4/0 AL to 2/0 CU and they are great.Hex screws allow you to torque these down really tight according to the specs included.These are about as small as possible - great for tight places.I put large heat shrink on wires before connecting and then wrapped the splice with several wraps of tape, then slid heat shrink down and heated.The hole is plenty big enough for 4/0 AL and the wire hole has a stop in the middle so you can be sure you get enough wire in each side.I typically use the fully insulated splices but couldnt get them this time so I tried these and they are great. Much smaller in length and costs much less.

This is a quality connector if used properly and torque to spec and use of the correct wiring of Course. Do you research and learn how to use the product properly.

East to install no chance for loose connection

Not true to size listed I stuck a picture with this post showing how much smaller the hole is compared to the 4/0 wire the whole seems like it's more for a 2/0 wire but I made it work couldn't get all these strands of the cable in the hole but got what I could to make it work