Manufactured by RSG, Inc. for Secutron, the DH line of door holders offers many features.. 

Very low current draw. Dual voltage inputs.
Terminal block connections.
High holding force.
Low residual magnetism.
Double chrome plating.
Mounting hardware & instructions. Optional Features
Double brass plating.
Extension and misalignment rods.
Surface mount back box.
Time saving drill fixture (for mounting catch plate).

The DH-24 series fire door holders are constructed of the finest materials and workmanship available.  The door holder is made of durable die-cast metal finished in high lustre double chrome or brass plating.  Other features include standard dual voltage dc or ac inputs of 12 & 24V, 24 & 120V and 24 & 220V models.  While reducing stocking requirements, the DH-24120 draws a mere .020 mA @ 24VDC lowering overall job costs (in large installations the cost savings can be substantial).  Other features: single or double coil floor mounting, surface mounting and direct wall mounting. No brackets are required. The DH series door holder offers a new installation technique using a adhesive template assuring alignment without secondary adjustments.
Accessories include extension and misalignment rods (various lengths) enabling parallelism between door and wall at distances greater than 12 inches and misalignment over 4 inches.

Aiding in installation is the aircraft quality DH drill fixture that reduces installation time and provides a near perfect alignment of catch-plate and armature, again lowering overall installation costs.

Basic units offer superior holding force and low residual magnetism. The DH-1224 and DH-24120 can operate at higher listed voltages producing holding forces in excess of 100 lbs (45.3 kg) for special applications.
 

Accessories

DHE1C 1" Extension Rod, Chrome

DHE1B 1" Extension Rod, Brass

DHE1.5C 1.5" Extension Rod, Chrome

DHE1.5B 1.5" Extension Rod, Brass

DHE2C 2" Extension Rod, Chrome

DHE2B 2" Extension Rod, Brass

DHE3C 3" Extension Rod, Chrome

DHE3B 3" Extension Rod, Brass

DHE4C 4" Adjustable Extension Rod, Chrome

DHE4B 4" Adjustable Extension Rod, Brass

DHE5C 5" Extension Rod, Chrome

DHE5B 5" Extension Rod, Brass

DHCPC Catch plate assembly chrome

DHCPB Catch plate assembly brass

DHDC Catch disc only chrome

DHDB Catch disc only brass

DHBBC Surface back box chrome

DHBBB Surface back box brass

DHW Extension wrenches (set of 2)

DHDF Drilling fixture 

 Download Data Sheet