This is where the auxiliary handle. Either the overpriced in my opinion the original part or just a replica, which is offered by vhbw.
The installation is quick in tripod mount, the grip is OK.
I've been using a diamond file broken something sharp edge on a handle, because I found the unpleasant.
Since I started using the handle continuously.
For anyone who wants to use heavy lenses of his Nikon V1, such a handle is worth a look.