Tension

From PBnJBassist (on the Internet):
 If you're looking for low tension flatwounds, I recommend any of the following sets from (get ready) lowest to highest tension, low-tension sets:

Thomastik Infeld 43-100
La Bella FX 39-96
GHS Precision 45-95
Ernie Ball Group IV 40-95
D'Addario Chromes 40-95
Sadowsky Black Label 40-100
D'Addario Chromes 40-100
La Bella 760FL 43-104
GHS Precision 45-105
Fender Super Light 40-100
Rotosound 77 40-100

*Left out other brands due to my unfamiliarity with them. Many apologies to the other flats out there.

Remember that all of these gauges are, for the most part, low tension, with Thomastik Infeld (TI) coming in at an average of 34lbs. while La Bella, GHS, and EB & Chromes come in very close with tensions ranging within the 37-39lbs. Once you break into Sadowsky territory and up, the tension is extremely minor with an average "feeling" of 38-42lbs. of tension. Basically, if you want the lightest of the light, go with TI flats, but if 3-5lbs. of tension is not going to be a significant factor with your playing style, then any of these light to light-medium sets are fine, fine choice.  And as always, select accordingly so that your brand matches your sound, as all strings (let alone flatwounds) are not made equally.