Centre crack chain guard questions

[Wayners]

What is this called?
Are they replaceable? Or specific size?
Just don't look great being plastic that's gone yellow.

Thanks

 

[saneagle]

Universal Bicycle Sprocket Protective Cover Bike Crank Chain Wheel Guard For MTB | eBay

Find many great new & used options and get the best deals for Universal Bicycle Sprocket Protective Cover Bike Crank Chain Wheel Guard For MTB at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk