Equivalent Products is what Grocery-Tracker uses to allow you to compare products that are similar, but not quite identical.  Using the Equivalent Products feature will allow you to compare products across brands and across stores.

In order to compare prices for different products, you must first define what products are Equivalent to other products.  Use the Product Catalog to define products as being Equivalent.
Some examples of Equivalent Products:
Here is an equivalent product.

As shown, Equivalent Product "Aaa Battery" was previously defined.

Please note that since this product is equivalent to another product, the "Primary" check box is not checked.
While in the Shop-Add screen, if you tap on the Equivalent Products button, you will be instructed to tap an item to find equivalents for.

Tapping on a product with the "Eq" flag will then display the equivalent products to the tapped one
Here, 5 "equivalent" products are displayed. The product with the lowest unit price will be displayed first, with each higher cost product displayed below.
You can then tap a product to add it to your list, or long-tap a product to display the prices at each of your stores.
Energizer AAA MAX Batteries
Duracell AAA Batteries
Duracell Long Lasting AAA Batteries
Energizer AAA Alkaline Batteries
Green Giant Corn
Libby Corn
Walmart Brand Corn
For price comparisons, you might want to define these as Equivalent.
Once equivalent products are defined, you can quickly view them while on the Shop-Add screen (Yellow Title Bar).  To view Equivalent Products, slide the bottom toolbar over until the "EQ" option is exposed.  Tap it and you will be prompted to "Tap" a product to find its equivalents.
Once a valid product is tapped (if there are no equivalent products you will be notified), the list will only display those products.  They will be sorted with the lowest unit cost first and the highest unit cost last.  The Store and Unit Cost will be displayed below each product.  The Lowest cost product will be highlighted in green.
The least expensive product will have its pricing and store information displayed in green.

Below the product desciption the following information is displayed:

Store, Units, Unit Price, Total Price
Simple to use! - Simply Powerful!
Equivalent Product Settings:

The "Normal" option handles equivalent products just like any other product.

The "Hide" option allows you to hide all equivalent products except for the "Primary" product. Using this option, you only manage the "Primary" product and any equivalent products are all dealt with as one product.

The "Expand" option only displays the "Primary" product, like the "Hide" option in the Shop-Add screen. The difference is that when you then tap on the "Primary" product, a pop-up list will appear displaying all of the "Equivalent" products. At that point, you can either tap the "Primary" product (it will be displayed at the top) or any of the products displayed.

The "Expand with Prices" option works like the "Expand" option above, but individual store prices are also displayed below each product.

The "Expand in Shopping List" option only displays the the "Primary" product. When an Equivalent Product is selected, it is added to your shopping list using the "Primary Products" name.
When you check the item off in your shopping list, the system will automatically expand the product to allow you to define what actual product was used and allows you to enter the correct price for that product.
Use the Product Catalog to define products as equivalent. 
The first step is to define a Primary product.  This can either be a normal product, or  a "Generic" name for a product.  An example of a "Generic" name would be "AAA Batteries".  An example of a normal product would be "Enegizer Alkaline Batteries, AAA".
First, define the generically named products, then make other products equivalent to them.

Please note that the the "Primary" check box is checked.
Also note, the "To Itself" check box is also checked.

All normal products have the Primary checkbox checked.
To get the most out of using Equivalent Products, use the "Display Equivalent Products" setting.

Non ProKey users have these 3 options.
ProKey users have these 5 options.
Please note.  There are 2 different ways to use Equivalent Products.
  1. Set All products as Primary products.
    1. This method is used to allow you to select Equivalent Products in the Shop-Add screen. 
    2. This does not change how the items are stocked.
  2. Set only the "Generic Named" product as a Primary product.
    1. This method allows you to select Equivalent products in the Shop-Add screen as well.
    2. Where this differs is how you treat your Inventory.
    3. Utilizing this method will stock the "Generic Named" product no matter what equivalent product is in your shopping list.
    4. The advantage to this method is that it allows you to maintain a single inventory point for all the Equivalent products.