DJI F450 adapters for 0.5" X525 aluminium arms

Warning!
If you are using the type of landing legs in the pictures (DJI landing skids), use all four screw holes! Depending on the frame, you may have to drill these holes. The landing legs will otherwise act as a lever when landing and eventually tear the adapters apart. This also happens on original DJI arms, but not as quickly, as they are injection molded.
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Update 29.01.2015:
All versions updated. Designed my own rear part of it (no longer taken from another source), made