I purchased one of these filters for my machine about 15 years ago and it has been worth it's weight in gold.
Before the filter my machine was constantly getting clogged and the pump that pumps out the water needed to be replaced a few times. Since having the filter I have never had any such problems. Same machine still going strong. Seems expensive but well worth it. If you clean it out after every wash the filter and your machine will last for years.