I have twin boys, and 2 Syma 107 helicopters for Christmas 2011. The helicopter is easy to fly, but early flying practice results in a few crashes and a few breakages. The black plastic part at the top of the Main Inner Shaft seems to be a weak point on these helicopters (couples to the upper blades). This repair kit gives you the bit you need for easy replacement of this component + replacement parts for other components too (I've also replaced 1 blade, a tail and 2 chevron shaped pieces in front of the tail). Good kit, gives you the bits you need and cheaper than buying individual replacement components. Also includes some replacement buckles which I've seen for a quid each in places. After a bit of practice the boys are getting quite good at flying. The helicopters would have probably ended up in the bin without this kit of replacement parts. You'll need a 0 or an 00 Philips screwdriver. Go for a Wera 00.