FOSC CW1988 has good Specifications in Sealing.
•Features
•Single-ended thermoplastic closure
•Base and dome sealed with clamp and O-ring system
•One oval entry port for looped cable
•Up to Four round ports for single cable entry/exit
•Heat-shrink cable seals
•Available with capacity up to 48 fusion splices
•Compatible with most cable types (single fiber or ribbon) and cable constructions (loose tube, central core, slotted core)
•One Tray with 12 core, Total 4 Trays Installed, up to 48 fusion splices