Intel S3700 SSD drives in Proliant Dl380 Gen 9

I was watching an Openstack presentation where they had in a DL380G9 22 SAS disks (I guess in the front bays) and 4 Intel SSD S3700 drives.

My questions are:

1- can non-hpe ssd disks be attached to the DL380G9? with what disk caddie?

2- This is a youtube video so, where were the 4 ssd attached? stacked one on top of each other and then plugged into where? 

thanks for your comments.

this is the image: 

DL380G9 w/26 disks