They just go right throu.
Only once.
Unless you do like I do sometimes and forget to unlatch the safety lock.
Been there. done that! I used to check the traps at dusk, around midnight and again at dawn. A few times I had traps that just sat there or were knocked over. ...... on closer inspection....ah crap!
Edit: Of course that is the same trap line I was running when I thought it was a good idea to cut across the ice instead of fighting the brush on the shore. Filled my waders clear full when I dropped thru! Cold walk to the truck!