These are the self tapping screws that hold the body on to the lower chassis.  They are M4.2 and 16mm long.  They are common on the Luba 1 and Luba 2.

Hexagon socket head self-tapping flat tail screw; M4.2*16

Part Number: F.100.SZ0504

Compatible Models: LUBA 1/LUBA 2