They are costly because HK makes so few of them. It took nearly 20 years of asking to get the Germans to address the issue with HK S/S levers being too short for many to move from safe to fire modes without having to first rotate the grip of the firing hand. They always claimed the S/S lever were short by design so one could not accidentally move the lever from safe by accident. While that might fly in Europe it does not in the US with experienced shooters. HK added it to the MSG90 ironically and then for the MP5's and other "Navy" style trigger groups for the US Secret Service MP5 submission. There are four different models of left side ESSL's with axels that are specific to the firing modes (SF, 012/013, NT, 2RB/3RB). That may not make the $140 easier to swallow but the fewer one makes the higher the unit cost due to the up front cost of the tooling.Yeah, I got the chance to play with one today.... Now it's a must-have.
That $140 is just tough to swallow for a selctor.
I'm slightly confused by their description.Centermass firearms has them in stock for a little less at 125 although their shipping is high ($12 via ups ground from NV to AZ... :\ ).
HK MP5 ESSL for Burst Trigger Groups Las Vegas Gun Dealer, Henderson , Indoor Shooting Range Las Vegas