This is a PvE D3-FNC Build. The build uses a ELE SP Backpack (this one contains the 2x Shield Damage Mods) swap for summoning the shield (the DPS Backpack with FA/ChD has 2x Sticky Bomb Radius - For Flash Bang). The shield damage mods are only used when the shield is created, so the Flash Bang radius is helpful throughout the actual play/usage (which is why it's on the DPS/play BP). Equip SP Backpack >> Summon Shield >> Switch back to DPS Backpack (repeat any time you need to summon shield again; like after exiting an elevator). This basically gives you the max shield, with the extra CHD. The alternative of setup (ie. SP on Knees, Backpack) without swap is just a shield at 1.9M instead (vs 2.35M when maxed; not a miracle, just a little extra shield HP).
The secondary MP5 can be used to regain your signature skill (or flashbang). If you are in a situation where it's had to get the kill-shot, you can use the pistol/side-arm (which has Coolheaded) instead. The pistol is GS228 (i32) so that coolheaded will be enabled.