what does the MKIISD update mean? the main update and why these are called MKIISD are that I took some improvements from the FGC9 SD and placed in the MKII shroud models that I designed. but keep in mind the are still made to just work with the MKII this is because the rail stands higher then the SD does. so the magnet design of the MKII have been removed. and the SD style magnet have been added. the to install it is basically the same. but you will be using a cylindrical magnet with a OD of 5mm and 10mm long in size. and wile I’m add it did I also add the grove that prevents the barrel from rotating -- for this model did I decide to go back to the fixed rail models. but the option for UNW LOW rail, and the normal MKII rail hight remains. the name 370 stands for the barrel length this is made for. but this is the same length as what was called the XL shrouds in the past like the: 2021 LB 14inch, 2021 LB 14inch, TEC9 XL, LB 14inch. for the barrel? you can use the ECM v3 set that can be found here https://odysee.com/@c0ld_d8rk_h8nd:8/ECM-Barrels-v3.5:e

Here is a 3D printable MCS Box Drive Dmag Tower. I found the price to expensive for a piece of plastic so I made my own. I have not field tested jet. but it seems to feed well. and it looks in place well on a MCS Bolt and Hurricane. note that it's a bit of a tight fit Link to the MCS Box Drive DMAG/HELIX Magazine Tower https://www.thingiverse.com/thing:3931853