This is U.S. Scott #2951-2954, the 32 cent Earth Day, Kids Care Block of 4 (in correct Scott order). This copy is MINT, NEVER HINGED, and the centering is FINE to VERY FINE (F-VF). (See the scan for precise centering.) It's a very nice copy with no issues that I can detect.
The block pictured is the actual one I will ship. I do not substitute copies.