714 AP2s swingweight

Can someone explain to me what swingweight means for the Irons?  

I got fitted for 714 AP2 and my specs were 1" longer, 1 degree upright with D4 swingweight.  I probably should've asked the fitter but didn't really pay attention to the D4 part.  I noticed on this website, D2 is the standard swingweight so what does it mean that the fitter recommended D4?

Swing weight is how the club will feel to you.  As clubs get longer or shorted in length, the swing weight will go up or down.  The Club Fitter recommended D4 to try and keep the swing weight down, so the clubs didn't feel too heavy at +1".  D2 would not have been achievable at that length.  Let me know if you have any other questions about this.

Cameron

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