The only difference between FM 1000 T and FM 500 T is the number of graduations on the dial face.
FM 1000 T has 200 graduations, each of 0.001 mm, whereas FM 500 T has 100 graduations of 0.002 mm.
Spindle and stem are made of resistant stainless steel. The spindle is lapped.
Made in Germany
Please see pg.36 & 37 of the catalog for more info: