Lens hood are primarily designed to stop light coming into the lens at extreme angles and being reflected inside the lens. 

This can lower the contrast of the image. 

Lens hoods also have two other very practical uses. 

Since the end of the lens is extended, you also get the added benefit of some extra protection from accidental impact, and also help to keep your fingers away from the front of the lens.

-49MM In diameter

-Material: 

 Ring is made of Black anodized aluminum 

 Hood is made of silicone

-Color: Black

-Anti-glare coating of the inner of hood for preventing the glare from getting into camera lens

Compatible models:

PENTAX smc A 50mm F2 Lens

PENTAX smc A 50mm F1.7 Lens

PENTAX smc A 50mm F1.4 Lens

PENTAX smc DA 35mm F2.4 AL Lens

PENTAX smc FA 50mm F1.7 Lens

PENTAX smc FA 50mm F1.4 Lens

PENTAX smc F 50mm F1.7 Lens

PENTAX smc F 50mm F1.4 Lens