11t-40t cassette is £33.59
Have you ever wanted to go 1x10 speed on your mountain bike, but not lose all your gearing and granny gears, get rid of the front derailleur and left hand shifter, running only one chainring onthe front, again saving weight on the granny and larger chainring assuming you have a triple,
well sunrace have created a 11-42t cassette, so you don't need an expensive expander cog (usually £27-65) and to split your current XT cassette, to set it up, buy this sunrace cassette it's far easier, regular price is £56
The 42t is a bigger cog than shimano s regular largest cassette cog 34t or 36t and so in simple terms you have lower gearing , which means you can run a slightly larger chainring on the pedals crank, and so you get a wider range of gearing otherwise you would have to lose out on lower (i.e. No granny gears uphill) or higher gearing (spin out on the road, descents)
I'm surprised this is on uber components sale add promo code UBER30 at checkout to get this price and it seems to be free postage.