To maintain the best performance from your net with minimal sag, the standard is to use one frame rib for about every 15' of net -- so for a 35' long cage you will need 3 ribs, for a 55' cage, 4 ribs, and a 70' cage will need 5 ribs.
However, it is also possible to limit the number of frame sections by increasing the thickness of the steel tubing, which will allow for your cable lines to be tighter - minimizing sag. Indoor cable applications only have 2 anchor points - on each opposite wall, spanning upwards of 100'. If you aren't able to install middle frame sections, or prefer to minimize the total number of holes in your ground, we recommend the Schedule-40 2-3/8" 2 or 3-section kit. This will allow cables to be anchored to each end, suspending your net like a shower curtain for support.
*Overall net size, thread thickness & material can all greatly impact the most appropriate number of sections needed to maintain optimal performance. i.e. a 35'L cage with #21 twine size will require less stability than a 55'L or 70' net using #36, #42 or #60 thread.
More nCage In-Ground Batting Cage Frequently Asked Questions