For the original German review, see here.
The case of the ADATA HD650 is made of a combination of a plastic body and a protective silicone cover. The latter protects the edges in case of an impact. The hard drive inside the case, a Toshiba MQ01ABF050 2.5-inch HDD, is protected by silicone as well. The plastic case itself has a surface pattern and looks like carbon. The HDD leaves a nice and high-quality impression if you do not look too closely. You can, however, see some smaller irregularities in regard to the gaps. Overall, the build quality and the stability are on a very good level.
We can measure a weight of 176 grams without cable (199 grams with cable) for the HD650 with a 500 GB HDD. This is pretty light, a 2 TB WD My Passport, for instance, weighs 231 grams (253 grams with cable). If this is still too heavy you could have a closer look at the external SSD SE720 with just 104 grams.
The box only contains the drive itself, a connection cable from the USB 3.0 micro-B connector at the HDD to the standard USB 2.0/3.0 type-A connector as well as an information sheet.