Schlage 35-157-1517-C 35 Series Operating Key Blank

Uncut. The 35-157-1517-C is a Schlage 35 Series operating key blank in the C keyway, so it comes with no bitting on it and has to be cut on a key machine to the cylinder you are pairing it with. That is why shops and facility key rooms buy blanks by the box: they cut to their own key system as rekeys come up. If you need a key that works the lock straight out of the package, a blank is the wrong item.

Only if those cylinders are C section. The 35-157-1517-C blank is milled to the Schlage C keyway, so it enters a C-keyed plug and nothing else. Being the same brand is not enough. If part of your building is keyed in a different Schlage section, a C blank will not slide into those plugs no matter how it is cut, and you would need a blank in the matching section for that group of doors. Buildings standardized on one section are the easy case: one blank covers every opening.

Look at the bow of a key that already runs the lock. Schlage stamps the keyway section there, and it has to read C for the 35-157-1517-C blank to enter the plug. No working key handy? A locksmith can read the section off the wards in the plug in a couple of minutes. Keep the two questions separate: the section decides whether the blank goes into the keyway at all, the bitting you cut decides whether it turns.

Just the key blank, nothing else. The 35-157-1517-C is a Schlage 35 Series operating key blank in the C keyway, not a cylinder, not a lockset, not a keying kit. If you are swapping a cylinder or rekeying an opening, order the cylinder and pinning parts separately; the blank only gives you the key stock to cut once the cylinder is pinned. Handing is not a factor either, since a key blank is non-handed and the same part serves left and right hand doors.