Product review (5 stars): Expensive but convenient
While the price is extremely high, the value is still there, especially having the piece that screws onto the bracket in the dryer.  This allows you to do the installation without removing the drum.  If you are side venting, knock out the bottom vent opening as well, it makes installation far easier, and taping the joint is easier.  Simply tape the bottom vent hole with foil tape when you are finished.  This is a job that a novice can handle.  Like others have said, use the foil duct tape, not the woven plastic.  I could have bought the venting items more cheaply as individual items but the aggravation factor would be much higher.  The best part is that everything sealed tightly and there is no warm air escaping under the dryer like it was when I side-vented my GE.  If you can swallow the price, it is worth it in not cutting yourself on rough metal edges.  There is no need to protect yourself from the side vents they simply pop out with a screw driver.  The bottom vent has sharp edges which you can cover with painter's tape while working.  I do not recommend gloves, you will need to be able to feel your way around the joint to tape properly.