M6-1 X 210mm キャップスクリュー | 六角穴付き | 部分ねじ | クラス12.9 合金鋼 サーマルブラックオキサイド (50本/袋)

The hex socket drive on these M6-1 x 210mm cap screws bites cleanly with a standard Allen key, no stripped corners. The 12.9 alloy steel feels dense and the black oxide finish is uniform across all 50 pieces.

Finally found black oxide bolts long enough for a deep clamping fixture I've been building. The hex socket drive made installation much easier than dealing with external hex heads in tight spaces. They feel incredibly rigid at 12.9 grade, which gives me real confidence in the assembly.

I needed longer bolts for a custom jig setup, and the 210mm length on these M6 screws was exactly what I needed. The black oxide coating feels robust and the partial threading made alignment much easier than I expected.