My NSS M1 vacuums have scrap traps-glad they do.The fan in an M1 is pretty tough-yes I have seen it eat nails and electric box knokout slugs with no problem.however the nuts,bolts and even parts sucked out of transmitters could even break the NSS fan.I don't want to find out how many quarters a Kirby fan can eat before breaking.I so remember a demo shown to me and Bill years ago at the Vacuum Cleaner Hospital by the Royal rep-He put the hose adaptor one one of the metal uprights and let it suck several pennies from his hand.then he opened the fancase-the fan only had a nick in one blade and another was only slightly bent.this would have DESTROYED a Kirby plastic fan.Yes,thats abuse-but it does show the toughness of the Royal fan.I won't do that.I use a canister vacuum most of the time instead of the hsoe on a Kirby or Royal for that matter.I just think the trap is an inexpensive and effictive solution against fan breakage-no it won't prevent it all of the time-but its better than replacing fans all of the time.Magnet bars are only good on steel itmes.Too many non steel items out there to break fans.I wouldn't even think of using a Kirby of any sort to clean up contruction-demolition mess.A shop vac or the M1.