Currently, Windows insider team is testing Windows 10 Redstone 2 PC build 14956.1000 and mobile build 10.0.14956.1000. The internal build 14956 is compiled on October 21, 2016. The cumulative update build 10586.639(Threshold 2), and build 10240.17157(Threshold) is also under testing.
Windows 10 1607 cumulative update kb3197954 build 14393.351 is available for release preview members. Windows 10 preview build 14931 is also now available for Slow ring insiders. You can download ISO from here.
Recently, Microsoft also rolled out build 14951 to fast ring insider members. Whereas, mobile users are facing download and installation issues. Now the company suggested few workaround for users facing problems. Link below.