Controlling exposures can be quite a challenge. You need your lamphouse to provide high light output so that exposure times are reasonable for large prints. But when making small prints, that amount of light can force extremely short exposures and/or stopping the lens down to a less than optimum aperture.
To address this problem, a set of three light attenuators was included with the C700 and C760 Dichroic lamphouses. An attenuator is inserted in the small slot in the top of the lamphouse to conveniently reduce the light output by 1, 2 or 3 stops, thus providing much greater flexibility in exposure times and lens aperture settings. Unfortunately, the attenuators are often missing when enlargers are resold, and were not included with the C760 Diffusion lamphouse. If you need to add or replace the attenuators, this is the complete set of three as originally supplied.