4.3 are just in a different league for CQB game play! They feel more nimble, allow for tighter cornering and cycle extremely fast. This is a great starting platform for you to build your dream build. We have already fully upgraded the upper assembly making it HPA & Tracer ready, put incredible aftermarket parts in to make sure you have the consistency to dominate the field. Build Spec List: Airsoft Masterpiece 4.1 LIMCAT Custom Slide Tokyo Marui 4.3 Hi-Capa Base Nexxspeed Airsoft Brass TDC Hop Unit PDI 6.01 113mm Steel Inner Barrel Dr.Black 4.3 Aluminium Guide Rod AIP 120% Recoil Spring Airsoft Masterpiece 4.3 Guide Plug Nexxspeed Short Stroke Set Dr.Black 'Dinging' Outer Barrel AIP 140% Nozzle Spring Cowcow B01 Blowback housing 4uantum GBB Hop Rubber Speed Airsoft Dual Hole Trigger Cowcow B01 Thread Adapter EDGE GIGA Magwell Cowcow Trident Sear Spring Airsoft Masterpiece SV Type 2 Gip Screws Frame Attachment Rail Tokyo Marui Magazine 12 Month Warranty on all built pistols - Items like Hop Rubbers, Nozzles, Nozzle springs are not included as these are consumable parts.