1/4" 內齒鎖緊墊圈 | 鋼鍍鋅（5000顆/包）

Ordered these for a batch of vibration-prone assemblies and the internal teeth bite into the bolt head noticeably better than the external style I used before. The 5000 count is a solid value for the price, and the zinc coating looks even across the batch, so no rust worries so far.

Needed a massive batch of #1 washers for a production run, and these zinc-plated ones held up perfectly under the impact wrench. The steel feels sturdy, and the internal teeth bit into the bolt head just right to stop any vibration loosening. Pack of 5000 saved me a ton of reordering headaches.

Bought these for a hardware rebuild on a vibrating machine and they held everything tight through a full week of heavy use. The zinc plating looks clean and even, no rust spots so far. For 5000 pieces at this price, I'm set for years.