These are the 4mm High Current Bullet Connectors from Castle Creations.
Fits wire diameter up to 4mm
Use 16 gauge to 13 gauge wires
Up to 75A current
Three sets of bullet connectors
Solder and soldering iron - HCAR0776 and STAR2000
Length: .66" (17mm)
Diameter: .15" (4mm) inside (where the wire is soldered to)
Diameter: .19" (5mm) outside
BOX DIMENSIONS: 3.00" W. X .25" H. X 3.00" L.
BOX WEIGHT: .03 LBS.