APS 13 mm, 120 Newtons spring
 
This spring is following the “APS 13 mm standard” (for 9 mm outside diameter spring guide). It will fit any rifle compatible with this standard, including all SRS (except push mechanism) and all TAC-41. While being compressed at 99 mm in length, it delivers 120 Newton (+/- 5%, around 9 Kg of force). This spring received a black electrophoresis coating, and a laser marking to quickly identify the spring.
 
Please Note
When buying parts from Longbow BB Ltd, you confirm you have the required ability to install and tech your airsoft replica as required. 
Longbow BB Ltd do offer a paid for service option for us to look at your rifle and try to solve any issues you maybe having. 
We need to manage your expectations as we (Longbow BB Ltd) are unable to provide extensive hours of tech advice for parts purchased that have been installed by yourself. 
All parts are inspected before dispatch to ensure product quality.