Applications for 56-1210 are:
Dellorto DHLA 40,45,48, K&N 56-1310
Mikuni-Solex 40,44,48 PHH, K&N 56-1310
Weber DCOE 45,48, K&N 56-1310

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

Product Specifications
Inlet Diameter    1.97 in (50 mm)
Mounting Hardware Included    Yes
Neck Flange    1.781 in (45 mm)
Replacement Filter    E-3321 
Top Style    Metal Chrome

Overall Height    2 in (51 mm)
Outside Length    7 in (178 mm)
Outside Width    4.5 in (114 mm)
Inside Length    7.072 in (180 mm)
Inside Width    4.572 in (116 mm)
Weight    1.3 lb (0.6 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 about K&N Custom Assemblies see K&N Assemblies: