What's the difference between Shimano cs-hg31 and 41?

[Custom24]

Hi
I need to replace my cassette. I've got a Spec Hardrock 2012, this one

http://www.specialized.com/gb/gb/bikes/archive/2012/hardrock/hardrockdisc#specs

I think the rear casette is a Shimano cs-hg31 8 speed, 11-34 (I just count the teeth to verify the last part, right?)

I'd like to get a cassette soon. Halfords have this
http://www.halfords.com/webapp/wcs/..._productId_951125_langId_-1_categoryId_165540

I am guessing it will work just fine?

Thanks
Mark

 

[lpretro1]

Will be fine