Yes, you would still need to sand those. as nigma said, it spreads the light. the only thing w/ those particular ones, is they have the 12v resistor already wired inline for you.
personally, i'd save money and hit up ebay for your desired color. Then a site like
http://www.opamp-electronics.com/~op...cPath=22_27_57
for resistors. That'd be the cheapest way to go.