These are Vintage spec tremolo springs which means that they have a slightly lower initial tension for a smoother first movement and then a slightly lower tension overall.  You also get much more control over the tremolo with less force needed to control it.

If you like the bridge static this is no problem you just tighten the claw and the bridge is static even with large string bends.

As an added benefit because you will be using 5 springs you get additional resonance from the greater connection to the body in the back, its not like night and day but acoustically there is an incremental improvement.

Modern springs are too strong which is why many people only use 3 or 4 whereas the Strat was designed to use 5 and still have a usable tremolo, if you use 5 modern springs you have to back the claw off to make it function but it requires some force to overcome the initial resistance and getting a smooth movement is not so easy.

These Vintage Spec Springs like those from the past have a slightly larger diameter than modern springs are are very slightly shorter, these changes do not affect the fit in a Strat at all.

One of the reasons that the arms break is because 5 modern springs are just too strong and too much force is needed to move the springs.

Specitication:

• STANDARD SET 5 SPRINGS
• FOR ALL TREMOLOS.