With the versatile Boker Plus MPP you are prepared for all situations. The pen serves primarily as a high-quality writing instrument, but can also save lives in extreme cases. In emergency situations, the glass breaker can help to free injured persons from cars or the stable body can be used for Kubotan techniques. The body with wide grooves is made of high-strength, anti-allergic titanium and is very comfortable to hold. The stable clip keeps the MPP always ready to hand. It is compatible with Fisher Space-Pen refills #Pr4, to change the refills it is screwed apart by left-hand thread. This prevents unintentional disassembly when unscrewing the cap. The diameter of the cap is 13.9 millimeters.