The B&G Strainer Kit - Part MS 145-50 contains both the strainer support piece and the 50 Mesh Screen as pictured on the website.
50 Mesh is used in the B&G AccuSpray with Termite Injection Tip - Part 24000101 and the B&G Strainer Kit - Part MS 145-100 (100 mesh) is for the Prime Line Sprayers such as the B&G Sprayer 1 Gallon 18 in. Wand & Extenda-Ban Valve.