The corners in black plastic into the GSM in place in case the break like glass from the first fall! (And again, and only very slight drop fell from the couch on the floor, or ± 50 cm)
the case is supposed to protect the device against falls (between-other) and does it well, but remember to replace it once his task accomplished.
Good protection but disposable plastic because not strong enough.
20 eur for the fall, it's expensive protection;)