These springs are the exact same trigger springs that are sold in my Spring + Trigger $35 packages. 
 
This is a replacement trigger spring for a PT111 G2/G2C/G2S/709 Slim and their 40 Caliber siblings that is about 20% stiffer than stock. A G2 Variant spring like this one is required to install any of my triggers in a G3 guns, and I recommended it in all of these guns. 
 
Here is my video on changing the trigger on a PT111 G2/G2C/G2S/G3/G3C: PT111 G2/G2C/G2S Trigger Replacement Walkthrough
 
Here is a closeup video covering an easier way to assemble the trigger, trigger spring and trigger bar: Trigger spring install for PT111 G2/G2C/G2S/G3/709
 
 
I often get asked why I only sell trigger springs that are 20% stiffer than the stock trigger spring, when many people are used to the idea that a performance trigger spring should be lighter than the stock trigger spring.
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The answer is that while many gun models can safely use a weaker than stock trigger spring to lighten the trigger pull, in these Taurus G2 variant/G3/709 guns the trigger spring does a lot more than just return the trigger forward, so having a stiffer trigger spring actively helps with the function and reliability of the gun. 
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In these guns the trigger spring is what actively supports the entire trigger bar and presses it upwards into the rear sear cage, which is how the trigger interacts with the sear and how the firing and reset functions. The trigger bar snapping upwards firmly is what gives you a good audible/tactile reset. In mild cases of trigger bar sagging the trigger reset wont be detectable, or the reset may be undependable, in extreme cases, the gun simply wont fire at all. 
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That trigger spring has a tough job too, because it has a very narrow grip spread on the very front of the bar, and then has to support the relatively long run all the way to the back of the trigger bar where it interacts with the rear sear. 
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The Taurus stock trigger springs are usually barely sufficient as long as everything is working optimally, but even in dead stock guns I have had multiple people email me for assistance with problem solving trigger reset issues.  Almost always these issues lead back to the stock trigger spring being too weak to effectively support the trigger bar, usually due to extra friction caused either by contact with the flexible polymer frame, from extra friction caused by even small amounts of foreign material, or even from running the gun relatively dry.
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So while my stiffer trigger spring is optional with the G2 variants and 709 Slims, I do recommend them for reliability reasons.