Hold up to the rigors of high tensile fencing and will withstand harsh weather conditions for 10-20 years. Zinc cog – Heavy-duty, compact design features a solid metal latch held down by spring wire. Strong, diecast zinc cog and hot dip zinc frame. Requires Strainer Crank (sold separately) to tighten. Aluminum cog – Features wire "flapper" for easy release. Zinc plated frame for extended life. Use 9/16" open end wrench or Strainer Crank (sold separately) to tighten.