HIGH QUALITY TO BE TRUSTWORTHY: 304 stainless steel material, not rust, anti-moisture, anti - oxidation, corrosion resistant, acid/alkali resistance, high hardness. No pollution, Health lead-free environmental protection non-toxic. STANDARD SIZE(Tolerance:±0.005mm): Uniform force, located in the center of the head with no offset, not easy to slip; Uniform pitch, obvious screw thread, no residual burrs, the set screw threads will be able to get a good grip.MANY SPECIFICATION TO BE CHOSEN: 1/4’’- 20 x 3/8’’、1/4’’- 20 x 1/2’’、 1/4’’- 20 x 3/4’’、1/4’’- 20 x 1’’、1/4’’- 20 x 1-1/4’’ 、1/4’’- 20 x 1-1/2’’ 、1/4’’- 20 x 1-3/4’’ 、1/4’’- 20 x 2’’ 、1/4’’- 20 x 2-1/2’’ ,total 288 pcs, Includes 9 Most Common Sizes. PLASTIC HEAT SEAL PACKAGING: Practical and convenient of packing box, All of screws and nuts are packed in a durable and sturdy box, this box can be use for a storage box. THE WIDE APPLICATIONS: Door handle, faucet, light fixture, knobs, locks and toys, , plumber and other small repairs around the shop, garage or home; and all kinds of precision machinery, classified instruments, electronic products, household appliances, communication products.