Generally speaking, netting panels are most efficiently installed within the structural area by being clipped/connected to a series of wires/cables that are tensioned between the support posts. The most recommended approach to to have wires or cables tensioned between the support structures in a way that creates a full-perimeter to clip the borders of the netting panel to. The same approach is used for both vertically-hung nets as well as horizontally-hung netting panels. The end result will be an even distribution of weight around the entire perimeter, as well as keeping the netting as "sag-free" as possible after it's clipped up.
For baseball and softball facilities, the most typically selected netting mesh size for barrier netting installations is a 1-3/4" diamond mesh pattern. The most commonly selected twine thicknesses are the #21 (2.0mm) and the thicker/stronger #36 (2.5mm) twine. From our experience, it's pretty much a 50/50 on which twine thickness that people go for, and they are both very functional and durable. The primary decision factors are often personal preference on the visual nature of the installation, preference on tensile strength, and budget. Netting panels can be provided by Gourock to any particular dimensions, and also most shapes. The materials used are DuPont® type 66-728 twisted-knotted nylon netting, and 5/16" braided Dacron® rope bordering (sewn-in).
Below are a couple examples of two custom netting panels that were shipped-out to a youth league establishment that required barrier netting to be installed horizontally to cover an area that was prone to fly balls and foul balls. Both nets were manufactured from the #36 X 1-3/4" (381 lb./twine) DuPont® knotted nylon netting with 5/16" Dacron® rope borders sewn-in. As you can also see, both nets have a customized trapezoidal shape and unique sizes/dimensions in order to match the customer's preferred installation area.