AKS-5 is a series of reed keyboard switches from Alps Electric. The reed capsule is positioned horizontally across the top of the switch at the back. The end result is a switch that—in the successor design, at least—is slightly too wide to meet the standard 0.75″ (19.05 mm) key spacing. Consequently, the switches are alternated 0°/180° so that the wide part fits into the space left by the narrower section.
AKS-5 is depicted and described in the article Reed-Type Keyboard Switches Offer Inherent Advantages by Tsutomu Osumi, published in JEE, August 1976. The specifications for the switch are not provided, but a lifetime for reed switches of 20 million switch operations is said to be guaranteed.
It is possible that AKS-5 was renamed KGF.
A switch type known only as alternating 0°/180° reed switches is the successor to AKS-5. This type replaces the thin plunger of AKS-5 (seemingly sheet metal) with a chunkier plastic plunger, and uses a smaller magnet. Although the revised design is unlikely to be DIN-compliant, it does appear to be shorter in height by maybe 20% or so.
The successor design may have been or become KGL.