This is a mount for the Amiga A590 Hard Drive Plus which should allow you to safely mount the SCSI2SD card internally.
There are two versions of the model. The first is for using a simple nut and bolt. The second is designed for brass inserts in the mounting holes.
The SCSI2SD card simply snaps onto the posts on the model.
I am using this with card version 5.1 of the SCSI2SD hardware but it should also fit the V6 card as well as it looks like the mounting holes are similarly spaced.
Edit: I have made a minor adjustment to the spacing of the card mount as they were slightly too close together to snap the card on properly without risking snapping the pins off..
I have also tested this on an A2091 card and it mounts properly there too.