Overview:
There is some hardware provided ( 3 gold-plated washers, 2 lock washers, 2 nuts per post).
There is a hole for banana plugs, and if you unscrew the plastic nut, there is a post for spade terminals and a hole for bare wire insert.
They are just banana plug jacks, or places to plug in banana plugs in the end or unscrew the thing and you can either put the wire through a hole in the post or wrap it around the post and screw the thing back down.

Features:
Dual female banana socket plug. One end for 5mm male thread connector, other end for 4mm banana socket.
Female Thread Dia. : 4mm/ 0.16";Size : 42x 15 x 35mm / 1.7" x 0.6" x 1.37" (L*W*D)
24k Gold plated. This connector is made by pure copper(Non-magnetic)
Professional made with good performance
Stable performance and easy to install

Package Included:
4 x Dual Female Banana Plug Terminal Binding Post.