Product review (1 stars): NOT FOR USE WITH A DRAIN PIPE SYSTEM!!!
Unless you have a drain tube, do NOT purchase this product. Your drain pipe will definitely back-up!!!  However, I only became aware of this after I received the product.  The manufacturer should have mentioned this in the advertising of the product.  Again, DO NOT PURCHASE UNLESS YOU HAVE A DRAIN TUBE!!!!  Using this product with a drain pipe leading into a wall will BACK-UP!!!