The PJHD181610RLF is the heavy duty member of the PJ fiberglass family: a Type 4X junction box with snap latches and a body measuring 18.24 in high x 16.24 in wide x 10.13 in deep. The series lists it as ideal to insulate and house off-grid solar batteries or remote monitoring equipment in outdoor applications, and well suited to high temperature or corrosive environments.

It is molded in UV stabilized ultraguard FRP material with 316 stainless hardware; the drawing specifies compression molded fiberglass reinforced polyester for box and cover. Wall thickness is increased to 0.200 in (5 mm). The enclosure protects from UV, dirt, dust, oil and water. Its gasket is a closed cell neoprene core encased in a continuous channel.

The cover is closed by four stainless steel lockable snap latches, which are pad-lockable, and swings on a stainless steel hinge and pin. The series gives a body and lid overall height of 12.1 in. On the back, two polycarbonate flanges fasten with stainless steel screws into four #10-32 brass inserts; the drawing gives mounting slot distances of 18.76 in (476.50 mm) minimum to 18.88 in (479.55 mm) maximum.

Optional inner panels are P1868 (white painted steel), F1868 (fiberglass) and A1868 (unfinished aluminum), mounted on four #10-32 brass inserts with plated carbon steel screws. The drawing lists back panel thicknesses of 0.100 in aluminum, 0.075 in white steel and galvannealed, and 0.125 in fiberglass. The PJHD181610RLF ships at 18 lbs (8.16 kg) and is REACH and RoHS compliant.