This cap fits all three sizes of Tilton Single-Chamber Plastic Reservoir Tanks (Part No. 3558, sold separately). Sold individually (two are pictured to show top and bottom views). This is the same threaded plastic cap as supplied in Tilton 74-Series and 75-Series Master Cylinder Kits (Part Nos. 3505 and 3506).
Note: Does not fit the Tilton three-chamber plastic reservoir.