How to use portable crop harvester with all attachments ?

What is the variations between 2 stroke and 4 stroke brush cutter ?, Why should I purchase 2 stroke portable crop harvester ? , Where to buy 4 stroke brush cutter online at affordable and best price ?, Who is the best weed remover in sidepack brush cutter or backpack brush cutter ?, Can be handpush or trolley brush cutter used as a crop cutter or weedeater ?Â