Overview Reviews Product Description WDM Bi-Directional SFP Module Supports WDM Bi-Directional technology, using a single strand of fiber, cost saving Product Videos Custom Field Product Reviews (No reviews yet) Write a Review Write a Review × TP-Link TP-Link SM321B WDM SFP Module WDM Bi-Directional SFP Module(LS) Rating * Select Rating 1 star (worst) 2 stars 3 stars (average) 4 stars 5 stars (best) Name *Email *Review Subject *Comments