The industry standard for supporting crops. Strong, polypropylene homopolymer plastic clips latch onto fine trellis twine to secure vining crops. The quick-release closure allows for easy adjustments as plants grow. Can accommodate stems up to 3/4 inch diameter. Clips are designed with side openings for improved ventilation.  David's Garden Seeds is a Veteran owned business that has been offering quality gardening products since 2009. Order Today! The string goes into the clamp, which holds the clamp in place and then attached to the plant which will hold the plant in place. I am a bit embarrassed to say that I have been selling/using these for years and just figured out how to use them a couple of months ago. I usually buy these from a reputable company. My last batch (I used in my greenhouse not for selling) I purchased from Amazon because they were cheaper. Well they do not close like the more expensive ones I purchase. It is very irritating. Cheaper is not always better. Depending on how hot it gets, these clips will last one to two seasons. Very seldom have I gotten three seasons out of them -- but that is probably due to our very hot temperatures here.