duravolt fifth wheel & travel trailer (class b&c rv) super magnetic for 1x 12v battery (upgraded model available - search asin b09885zrwr)- no experience plug & play duravolt new higher power duravolt fifth wheel & travel trailer (class b&c rv) magnetic battery maintainer 12 volt 10.0 watt - no experience plug & play design. dimensions 11.8" l x 10.0" w x 1/4" thick. 10' cable.