30PCs 1/4"-20 Stainless Steel Rivet Nuts Flat Head Insert Nutsert 1/4-20UNC

Do you have 1/4-20, or other size, with 0.25" grip range?

What size bolt thread are these used for example 6mm?

How do you know which end the screw goes in? Seems like ads for rivnets dont differentiate which type you are buying.

Can a bolt be threaded from the opposite end of the nut? I understand that this is not the intended purpose.