SSND-MRB 16-21
Recommended for open bore options
SSND-MRB 16-21 is one of our largest and most substantial silicone sounds, engineered for advanced users exploring progressive volumetric expansion and deep-canal stimulation. Spanning a full 13" in insertable length, this piece features a sequence of 14 distinct, rounded sensory bumps that gradually expand from an initial 16.6mm up to 21mm near the base. The alternating peak-and-valley profile creates a rhythmic, wave-like sensation as each segment traverses the urethral canal, terminating at a 21.1mm safety flange for depth control.
Anatomical Sizing & Mechanics
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Progressive Expansion Geometry: 14 distinctly sized, smooth bumps transition gradually from 16.6mm (50 Fr) at the tip to ~20.8mm (62 Fr) at the base.
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Alternating Valleys: Deep, contoured valleys between each bump provide dynamic pressure release and allow lubricant to track evenly during movement.
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13" Deep-Tract Length: Sized for full-length exploration, navigating the anterior and posterior canal into the deep prostatic pathway.
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21.1mm Safety Flange: Sits at the proximal end to provide a secure external depth stop.
Anatomical Depth Guide
With an impressive 13" (330mm) insertable length, SSND-MRB 16-21 is built to traverse the entire urethral pathway. The gradual scale of the 14 bumps allows tissue to adapt progressively as deeper, larger segments pass through the bulbar curve and external sphincter.
Detailed Bump & Valley Measurement Table
| Segment # | Peak Bump OD (mm / Fr) | Valley OD (mm / Fr) |
| Tip | 16.6mm (50 Fr) | 11.5mm (34.5 Fr) |
| Bump 2 | 16.8mm (50.5 Fr) | 10.9mm (32.7 Fr) |
| Bump 3 | 17.0mm (51 Fr) | 12.6mm (37.8 Fr) |
| Bump 4 | 17.7mm (53 Fr) | 13.3mm (40 Fr) |
| Bump 5 | 18.4mm (55 Fr) | 14.1mm (42 Fr) |
| Bump 6 | 18.9mm (56.7 Fr) | 16.0mm (48 Fr) |
| Bump 7 | 20.2mm (60.6 Fr) | 16.6mm (50 Fr) |
| Bump 8 | 20.6mm (61.8 Fr) | 16.6mm (50 Fr) |
| Bump 9 | 20.7mm (62 Fr) | 16.6mm (50 Fr) |
| Bump 10 | 20.6mm (61.8 Fr) | 16.1mm (48.3 Fr) |
| Bump 11 | 20.9mm (62.7 Fr) | 16.1mm (48.3 Fr) |
| Bump 12 | 20.6mm (61.8 Fr) | 16.8mm (50.4 Fr) |
| Bump 13 | 20.8mm (62.4 Fr) | 16.7mm (50.1 Fr) |
| Bump 14 | 20.8mm (62.4 Fr) | 15.0mm (45 Fr) |
| Base Flange | 21.1mm (63.3 Fr) | — |
👑 Bob's Choice Recommendations
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Experience Level: Advanced
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The Prime Durometer Recommendation: #00-50 (Soft) is the strongly recommended durometer for this large-profile sound. In #00-50, the large 16mm–21mm bumps remain highly compressible, allowing the material to yield and squeeze during insertion while applying a constant, uniform outward expansion force against the urethral walls. Because #00-50 silicone is soft and flexible in a large, 13" length, it requires ample lubrication and a slow, patient insertion technique to navigate the canal effectively.
Color Options: #18 and #30 are available in pure translucent. #00-20, #00-50, and #10 base colors are translucent white and can be mixed with any standard color.
⚠️ Important Safety Disclaimer: Because individual anatomy varies, we cannot guarantee a full fit for all longer or larger diameter pieces. Please use all products with care. By purchasing, you accept full responsibility for safe use. If you experience discomfort, discontinue use immediately.