K&N Custom Air Filters for Single or Two Barrel Carburetors - K&N custom air filter kits are designed to boost performance from your carburetor while keeping the dirt on the outside where it belongs. These assemblies come with custom chrome top and base plates and the famous K&N High-Flow Washable Air Filter.
 

Note that these here apparently fit Dellorto DHLA 40,45,48:
56-1310, 56-1320, 56-1330, 56-9345
 

Product Specifications
Air Filter Height 1.75 in (44 mm)
Inside Width 3.75 in (95 mm)
Air Filter Inside Diameter 7.375 in (187 mm)
Outside Length 8.875 in (225 mm)
Air Filter Shape Oval
Inlet Diameter 1.97 in (50 mm)
Mounting Hardware Included Yes
Overall Height 2 in (51 mm)
Replacement Filter E-3441
Top Material Chrome/Metal
Size 6-9

Weight 2 lb (0.9 kg)
Product Box Height 6.75 in (171 mm)
Product Box Length 10.5 in (267 mm)
Product Box Width 8.38 in (213 mm)

More info about K&N assemblies Click Here