How large need homology arms to be? - (Feb/07/2017 )

I would like to insert a 2808 sequence bihind a gene by CRISPR/Cas9 homology repair. Are 800 bp-homology arms large enough or should they be larger?

Thank you

LP

800 bp is usually enough for these sorts of things. In theory you should be able to get away with  much shorter - as little as 100 bp possibly.