Do you mean air or coil?

Check steerer tube size (1-1/8, 1.5, or tapered...you may be able to put in a reducer headset if your headtube is too large), check to see what kind of front hub you have unless you want to buy a new front wheel, make sure the steerer tube hasn't been cut too short, check the axle to crown measurement to see if it's comparable to your bike or that it'll change the geometry in a way you want.