Thanks for the quick reply and specific advice.
To answer your questions, our walks are in major cities, guides stand outdoors, pointing to buildings up to 2 miles away, but generally closer.
Since my first posting, I've read just what you write - that Green 5mW is plenty good.
But can it cost just over $10?! Will the lamp work for a long time?
And also, do I need to worry from the start what batteries to choose to power the pointer?
Anticipated thanks.