These premium concrete knurled drop anchors are made from safe materials and are enough to last a long time. Good workmanship and easy to install, just use the power drill and insert the bolts into the holes. Hit with a hammer and then screw on the bolts, giving you a great of convenience. Features -Color:Silver. -Material: Carbon Steel. -Size:4.00X1.10X1.10cm/1.57X0.43X0.43in. -Note: Suitable for 3/8-40 bolts. - These premium concrete knurled drop in anchors are made of safe materials, and can be used for long time. - There is sufficient quantity which can fully meet your different needs, very professional and practical. - Good workmanship, high hardness, sturdy and strong, can be fixed very firmly to concrete. - Easy to install, simply use the electric drill hole, and then insert the bolt into the hole. Hit with a hammer, then screw on the bolt. - Commonly used with machine screws, bolts and threaded rod to anchor fixtures to concrete and other materials. Package list: concrete knurled anchors