this where i get confused, which is why i asked

50kg x 7 = 350kg plus safety factor 50kg so i need an S hook rated to 400kg, close to a 1000lbs.....

the only S hooks i can see are rated to about 100kg and the snap shackle people post pics of seems identical to the 1 in the shops i see rated at 120kg.....

the shackles that are doing the job now are probably only rated to 120-150kg, divide by 5 - means either i am pulling less than 30kg, possible, or the shackles are very conservatively rated and are working very near their rated values...

edit....i see the muurays snap shackles on pg31 are rated to 1000lbs

http://www.murrays.com/archive/31.pdf