U.S. Endicott-era balanced pillar and masking parapet mounts were, in a sense, a hybrid of simple pedestal mounts and disappearing mounts: the guns were hidden from observation while out of action, but, once engaged, remained vulnerable to direct observation and direct fire. The emplacement designs only permitted retraction with the gun barrel at a specific traverse angle, usually 90° off the emplacement's axis. Since the barrels substantially overlapped the parapet of their installation, it was impossible to point the piece while concealed. The balanced pillar mount was used primarily with the 5-inch gun M1897, while the masking parapet mount was a Driggs-Seabury patent used primarily with the manufacturer's 3-inch gun M1898. "Masking parapet" was a proprietary term coined by Driggs-Seabury to distinguish their carriage from balanced pillar designs. Beginning in 1913 these carriages were disabled in the "up" position due to undesired flexibility interfering with aiming. The M1898 3-inch gun also developed a tendency for the piston rod to break when fired, and both types and their associated guns were removed from service in the 1920s.