ps. the only thing i found useful for me/us is a 3-in-1 (mul-T-Lock) Lock core. $5xx for a lock but it can 3 different cores. We can use it for give the first key for inspection and then disable the first key after finish inspection without buying another new lock
but i read from other property owner
his 3-in-1 key lock had suddenly change from key #1 to anothoer two
fortunately he had brought all 3 keys so he can open the door
but when buy the 3-in-1 user can get all 3 keys wor...
ps. suddenly change from key #1 to anothoer two? the sales explain that it change only when user use key 2 to anti-360 degree lock the key core. then it will become key 2 function.