Gammon Reels
When you want to save time with setting up your tripod and instrument, a retractable Gammon Reel can save the day. Pull the string out as much as you need, slip over your plumb-bob and then retract the length as needed depending on the height of your tripod. As you know, each setup can be set the tripod at a different height from the ground, as well as your pin can be a different height, hence the need to quickly adjust the length of your plumb-bob string.