These are what are known as ball and seat injectors ! You will see they have an en code number on the injector! This matched upon install on many MB engines to the ECU and known as it IQA--Injector Quantity Adjustment. (Use of a scanner. to program) That adjustment is derived from the injector in question being placed upon a special test stand that sets the NEMA code which is a fine calibration of the injector and the code given onto the electrical cap which sets the shot discharge to meet your engine's specs through the ECU. Hence if you remove an injector don't mix em up! They are cylinder matched . If you take one apart you will have disturbed the NEMA code and it will need to re calibrated for a new IQA number . Care! Water in the fuel and dirt are the injector's enemies plus you with careless handling! The injector should be capped off once opened! Do not leave the injector open to the elements. The same goes for injector pipes and rails! Always blow out the injector pipe with compressed air before install and NEVER attempt to bend the injector pipe . it will exfoliate the interior of the pipe and allow minute metal fragments to damage the vulnerable ball and seat control valve wrecking the injector at the pressures they work at! These Bosch ball and seat injectors are/ were commonplace on many engines not just MB products. They have fell out of favour in 2006 but a recent Bosch seminar indicated they are coming back to oust the now popular Piezo style injector' These ball and seat injectors are also shared by Cummins 5.9 4 valvers --GM Duramax--Some Fords to name a few. Happy Motoring Tuercas Viejas (Fixin' diesels since 1956) .