The model 37 is the airweight version of the Model 36 Chief's special. The frame is an aluminum alloy while the barrel and cylinder are steel.
If you have to carry a gun day in and day out with low odds that you'll need to use it, the 37 is fine. But their light weight make them difficult to shoot accurately due to the recoil, especially with +P ammo.
Most of these guns are not really rated for +P ammo unless it is a model made after about 1991. Use of +P ammo has been known to cause frame stretching which leads to a "loose" gun. In the 60's and 70's we referred to them as "Carry lots, shoot little" type guns.
With all that said, they're fine, reliable guns of excellent quality. But they are not mean to see 200 rounds a week through them either.
The model 37 also makes an excellent back-up gun. The light weight eases the burden of carrying a 2nd gun.