Thresholds are mounted directly below the shower door to let the water drain back into the shower stall. Ideal for flat or out-sloping curbs/the rounded low contour of the Half Round Threshold will not harm feet. This threshold may be used in conjunction with a bottom sweep. Use Mildew Resistant Silicone Sealant to adhere to curb of shower stall. Is sent as a 36″ length and will have to be cut to size by the purchaser.