A: Here is a summary from the Schlage website:
HIGH SECURITY
Primus/Primus XP: In addition to six cuts for standard locking mechanism, there are five side finger pins to operate the secondary sidebar lock. Primus keys will operate non-Primus locks within the same system. Primus blanks and keyways are slightly thinner to prevent the entry of non-Primus keys, however even if a standard key is altered to allow entry, it will not operate Primus locks. This design was protected until 2007 under US Patent # 4,756,177. The current generation Primus, called the Primus XP is a slight modification to the original design and is protected until 2024 under US 7,159,424
EVEREST
Everest 29: Everest 29 offers the highest level of restricted key system security by Schlage through patent protection of the keyway design. Patent protected key systems prohibit key duplication and assist a facility owner manger in maintaining key control. The new patent enables a key blank that is backwards compatible to the current Everest design allowing Everest 29 keys to work with existing Everest systems aiding the key system migration process. There are both a Utility patent and a Design patent for Everest 29. The Utility Patent # is 7665337 and is protected through Feb 18, 2029. The Design patent for the bow shape is protected until Jun 20, 2026.
Everest: Features a patented under groove in the keyway design protected against cloning by utility patents until July 20th, 2014. Relevant patents are: US 5,715,717 and US 5,809,816. Just like the classic series, Everest Primus keys can operate Everest non-Primus locks, but not the other way around. Everest Primus XP is an extension to Primus Everest and the XP design is protected until 2024 under US 7,159,424
SCHLAGE CLASSIC
Obverse: The most common type. The common residential hardware keyway that competes directly with the Kwikset KW1 is known as 35-100C or referred as SC1 in EZ code.
There are 7 different keyways C,CE,E,EF,F,FG and G. There is a special "P" keyway designed to accept any of the 7 keys and a special key blank designed to be accepted into all 7 keyways, 35-101 L which is made of stainless steel and requires a special machine to cut.
Reverse(restricted): Horizontal mirror image of obverse keyways, no longer offered in new key systems and it is not available with Primus option.
Numbered(restricted): A large family of keyways expressed as four numbers. You can only have the same number once, except zeroes in the keyway designation. i.e. 3578, 1358 and 1200 are valid, but 1244 and 3300 are not. Primus cannot be implemented on this series.
Quad(restricted): Expressed in four characters, such as WSTP, VTQP, etc. This is a very large family and also available in Primus.
Q: Is the H section key strong? I know the L section key is pretty weak and the key and break sometimes