You can update Products Attributes for multiple products at once, from admin page.
It works with an infinite number of products.

You can load a set of existing attributes that already belong to a product, for update/replace for other products.

You can filter products by the following conditions:
- Product Name
- Product Tags
- Model
- Categories (multiple selection is possible)
- Manufacturers (multiple selection is possible)
- Filters (multiple selection is possible)
- SKU, UPC, EAN, JAN, ISBN, MPN, Location
- Price (base price)
- Discount: Customer Group, Price, Date Start, Date End
- Special: Customer Group, Price, Date Start, Date End
- Reward Points: Points (Number of points needed to buy a product), Customer Group, Reward points
- Tax Class
- Quantity (stock)
- Minimum Quantity (Force a minimum ordered amount)
- Subtract Stock
- Out Of Stock Status
- Requires Shipping
- Date Available
- Date Added, Date Modified
- Status
- Store
- Attribute, Attribute Value
- Option, Option Value

Products for update:
Filtered products will be listed with pagination, so, it works with an infinite number of products.
You can set how many products shown per page (for slower servers or large databases, it is recommended a smaller number of products per page).
You can deselect or reselect certain products from list.

You can load a set of existing attributes that already belong to a product, for update selected products.

Products Attributes Updating can be done in the following ways:
- Keep all EXISTING attributes and its EXISTING values and add/update the NEW ones. (If a new attribute already exist, its value will be updated.)
- Remove all EXISTING attributes and its EXISTING values, then add the NEW ones.
- Remove EXISTING attributes and EXISTING values that exactly match with SELECTED attributes and SELECTED values. (Will not be added anything new.)
- Remove SELECTED attributes (and all its values) (Will not be added anything new. No need to set new values; in this case they are not used.)
- Remove all EXISTING attributes and all its EXISTING values. (Will not be added anything new. No need to set new attributes or values; in this case they are not used.)
- Remove (clear) all EXISTING values. (Will not be added anything new. No need to set new attributes or values; in this case they are not used.)

Admin LIVE DEMO
username: demo
password: demo

In instructions.txt file from downloaded archive you will find full instructions about installation and usage.

Related extensions:
- MASS Products Update PACKAGE
- Admin Advanced Products Filter
- Admin better autocomplete
- ADMIN: Add Category Filter and Categories Column in Product List

Also, you can find this extension in MASS Products Update PACKAGE