One of the finest springs money can buy.
These Variable Pitch sprtings (also called Non-Linear or Progressive) are hand made in Japan from Silicon Chrome Steel and have one section of slightly tighter coils to reduce the initial stress on the gears and piston.
They are generally shorter and stronger than most Non-Linear springs so give a more stable power output and last much longer.
These are rated as a percentage of the standard Tokyo Marui springs (0.81J) and are listed with their approximate Joule rating and the equivalent fps with 0.2g BBs.
As with all springs, the precise energy output will vary depending on your exact setup so if you're unsure as to which one would be most suitable, feel free to drop us a line.
We don't generally recommend using very weak springs for most builds, a stronger spring with short-stroked gears is a much better option to achieve under 350fps.
PDI Perfect Pitch AEG Springs
Please note that the rated power levels are assuming perfect efficiency. This generally means that these ratings are the maximum attainable power output for each spring strength so you may need to go up a step depending on your build.
These springs can work in TM NGRS gearboxes however some may require trimming down.
You can check the fitment by installing the spring into the piston and compressing the spring using the spring guide.
The spring back of the spring guide should be able to touch the back of the piston; of it does not please trim the spring and refinish the end until it does.
Drop us a line if you'd like any advice on choosing the best spring for your build.