This is the fullsize MP5. RDTS did 110% of the work on this weapon. 4pos/3rd burst ambi lower, paddle mag, correctly remarked, and with full stock, very comfortable to shoot! Registered sear gun, so you can move the sear around to one of your other fine HK hosts! Also registered as a SBR. This is a 2 tax gun! Collapsible stock(pictured) available for purchase for an additional $595. The sear is an S&H Sear.All HK's are shown with a 4 position/3rd burst lower. These are not included with the price. Guns all ship with plastic S-E-F packs. If you wish to upgrade to the 4pos/3rd pack, please add an additional $1795.