A ring of x-ray vision empowers its possessor with the ability to see into and/or through substances which are impenetrable to normal sight. 

Vision range is 20-ft, with the viewer seeing as if it were normal light due to expanded vision capability. 

X-ray vision will penetrate 20 ft. of cloth, wood, or similar animal or vegetable material, up to 10 ft. of stone or 10 inches of many metals:

It is possible to scan 100 square feet of area during one round; thus, during 1 turn, the wearer of the ring could scan a full area of stone 10 ft. wide, 10 ft. high and 10 ft. thick, or 100 ft. wide, 10 ft. high, and 1 ft. thick. 

Secret compartments, drawers, recesses, and doors are 90% likely to be located by x-ray vision scanning. 

Even though this ring enables its wearer to scan secret doors, traps, hidden items, and the like, it also limits his or her use of the power, for it drains 1 point of Constitution if used more frequently than once every 6 turns. If it is used 3 turns in 1 hour, the user loses 2 points from his or her total Constitution score, 3 if used 4 turns, etc. Constitution loss is recovered at the rate of 2 points per day of rest. Constitution of 2 means the wearer is exhausted and must rest immediately. No activity, not even walking, can be performed until Constitution of 3 or better is restored.