Jim Sweeney:
A regulation metal hole liner is used on all of the greens. The greens sand is approximately 24- inches deep and is compacted quite well. With the oil in the top 1-2 inches of the sand and with the compacted greens sand, the "lip" of the hole liner usually remains in good shape for one week before they are changed again.
The "nudge" of the golf ball on either side of the rope on top of the bunker does not count as a stroke as per a local rule.