yup, i'm using these length is adjustable by cutting off the extra length of the lower eyebolt these are standard 1/2 threaded bits, available in several lengths i bought a bunch and experimented
on some corners i cut the eyebolt to make a hook out of it, on other corners i used carabiners to get the right length
not really spring loaded, but strongly cammed, and they have a large safety pin
on some corners i cut the eyebolt to make a hook out of it, on other corners i used carabiners to get the right length
not really spring loaded, but strongly cammed, and they have a large safety pin