The rails supplied with my APC AV device are too long for my AV rack enclosure.
APC AV S-type Power Conditioners w/ Battery Back-UP
All of the previously listed products.
These units were initially shipped with a rail kit designed for standard IT racks. This was found to be inadequate for many AV specific racks.
APC has developed the SRAILKIT for mounting the APC S Type AV Power Conditioner with Battery, into any four post racks with depths ranging from 20"" to 28"". The kit includes an Installation guide, Mounting Hardware, Rack Mounting brackets and Screws.