A keyed removable mullion from Von Duprin now carries the UL fire label for openings up to 8’0″. It delivers single-door performance and security on double fire-door applications. When large equipment or furniture must pass through an opening, it makes mullion removal a simple key cylinder operation. The unit will self-lock when re-installed, without the need to re-use the cylinder key. The new assembly is available in Von Duprin’s 1654, 4954, 9854 and 9954 steel mullions. The mullion assembly is ideal for exterior doors and has been tested to over 10,000 operations. It also has passed static load and impact test