It seems most company's use 2
I have Asr a-arms for about 4 years now. I had a no name -2 swingarm, that I had snapped in 2 places in glamis last year. I called Asr and got -2 full gussets skid plate brackets and brake line for 5 and change. Called JJ&A and got a refurb red carrier which was like brand new, I swear they call them refurb for no reason..