Made of brass material, anti-corrosion and durable. The grease zerk nipple mouth is flat and smooth, great for fastening. The thread is deeply, thread pitch more sturdy, it will not slippery when rotating. One sprung ball check prevents entrance of dirt. Suitable for most automotive, motorcycle, truck, farm, and industrial applications. Please check the size carefully and make sure this is the correct part for your unit before making payment. Package included: 6 x grease nipples