I had to get a 19t cog and chose to go with EAI since alot of people run them. I got the regular deluxe cog. Now I know, "a cog is just a cog", but I have 2 surly cogs and they seem alot beefier than the EAI. Im not saying I put out enough watts to bend and break the teeth but it just seems like the EAI would be burlier. The Surly cogs are a bit thicker, and seem/look stronger. And the Surly has lightening holes. Im NOT bashing EAI, im just surprised. I do want one of their gold cogs at some point though.LOL