It's called basket strainer for its basket-shape strainer screen which is different from other screens. 
1. Basket strainer is applied in pipeline for oil and other liquid to filter sundries in the pipeline. The area of its filtration sling is 2-3 times bigger than area of bore size pipeline. 
2. Basket strainer is mainly composed of adapter, cartridge body,strainer basket, flange, flange cover and fasteners etc. 
3. The sundries in liquid in the pipeline is collected to the filter screen by strainer when liquid flow through the strainer. The cover shall be opened and the screen shall be cleaned in a certain extent.