i started out throwing the trimmers in the back of the truck which ended up smashing the fuel tanks and breaking off carbs and spark plugs.
so i got a brand that need u to put in long pins to keep the trimmers in worked ok at first then the pins started to get lost and the trimmers kept spinning in the racks and would flood and rip off the throttle cable.
so i gave them away and got a spring loaded type rack very popular brand which would hold the head end in a funky piece of bent metal and held the trimmer good for the first few weeks then started to let them spin and wore the end of the trimmer shaft and even bent one when a employee couldn't work the spring and pulled on it and bent the shaft all to hell.
over the years i have had more damage done to my trimmers from the stupid racks then from using them to trim with.
and none of them lock good enough or easy enough to keep the guys locking them seems they never do no matter what i give them.