Patented PostMaster spades are Kimber Kable's assault on the ultimate spade design. Machined from ultra pure copper and then coated with Kimber's proprietary UltraPlate, these spades feature a unique compressible wafer between the contacts that maintains dynamic pressure on the binding post with only 'finger tight' torque. No need to use a wrench! Maintaining a constant pressure is important because it prevents impedance fluctuations due to vibration and temperature changes. Pressure ridged on the spade help to insure a gas tight seal and reduce contact resistance.Kit consists of 4 PM spades, 4 heat shrink color-coded sleeves, and two lengths of high purity silver solder.