Barton Marine Size 2 Single Upright Block [N02150] Brand_Digital Antenna You can also use this

You can also use this hefty little block to combine the ground wires of four (4) sources to a single grounding point

Inside Dimensions: 10-7/16" L x 6-7/8" W

Box Dimensions: 2"H x 4"W x 6"L WT: 19

Power options: two D batteries

LED lights and intake/exhaust switch

Barton Marine Size 2 Single Upright Block [N02150] Brand_Digital Antenna You can also use thisSize 2 Single Upright Block Plain Bearing Blocks Barton plain bearing blocks have a precision molded acetal sheave running on a large diameter brass bearing, ensuring free running under the highest of loads. Specifications Sheave size: 35mm x 12mm Max rope diameter: 8mm Safe working load: 370kg 815lbs Breaking load: 740kg 1630lbs Length: 80mm Weight: 73g