The Chimera Large Daylite Senior (54 x 72") is the largest, most durable softbox Chimera makes. It is designed for use with a Fresnel up to 24,000 W with a front diameter between 24 and 29". It utilizes an extremely deep profile of 50". The extra depth of the Daylite Senior (it's about 30% deeper than the Quartz softboxes) allows the Fresnel beam to spread out and cover the front face more evenly. This extra depth, combined with a fabric that is even more heat resistant, makes the box safe when used with a 24 K light.
The "Plus" designation means the front face is removable. Chimera makes different strengths of diffusion material for front face applications. The softbox comes with a one-stop diffusion cloth and additional 1/2 and 1/4 grid cloths. Substituting a half or quarter diffusion or taking off the interior baffle would result in even more contrast, slightly more light transmission and less softening of the light.