Evaluation of the Bon4M Metal Chastity Device for Wearers and Tinkerers

Here is my review of the Bon4M (standard size) chastity device I got about two to three weeks back. I’ve come across a few reviews, but this community seems geared toward “tinkerers,” which fits me and my search for “the perfect device” perfectly well. I’m sure some of you understand what I mean… Some background context to help place my experience in perspective. I have moderate experience (around 5 years), my wife acts as the key-holder, and we cycle on and off every couple of months when it counts. When locked up, I am essentially in continuous wear, so long-term comfort is essential. I’m near fifty, in good shape, average build, a grower with no piercings. Previous devices include CB-2000, 6000, 6000S, Mature Metal, and Neosteel. Currently, the CB-6000 paired with a KSD G3 anti-pullout add-on from Kept of Her has been my top choice for balancing comfort and security. Like many chastity enthusiasts, I’ve kept looking for better security without sacrificing comfort or requiring piercings (which would be unacceptable to my wife). The Bon4M caught my eye because it resembled my current favorite (the CB-6000) but offered potentially higher security thanks to its metal build. My hesitation with the CB-6000 is that I can just snap it off if things get too frustrating; this mental block affects me. Also, the Bon4M seemed reasonably priced for a metal device, so buying one for testing purposes was no big deal. Kept of Her had also told me their KSD modification (by another user) works well with this model—something I viewed as vital since most other ball trap devices without the G3 feature are too easy to escape from given my anatomy. At least I need to be able to pretend I’m locked in for good to get into the right headspace. The ordered device arrived from China roughly three weeks ago (14 days between order and delivery). IMPRESSIONS Overall, this is one of the better value metal devices I’ve owned or seen. It arrives with some issues (detailed below) but feels very similar to the CB-6000 which I really like. The fit/finish on the outer surfaces seems acceptable, while the inner surfaces are less so—especially inside the cage. I didn’t even try wearing it until I spent time grinding, cleaning, and polishing. If you’re handy with a Dremel, I think this can become an excellent device (maybe even “the one”) after some work. In my view, it is NOT ready to wear straight out of the box—too rough for long-term use or even just a weekend. So here’s what I did to bring it up to speed… Cage: My wife and I both like the design quite a bit, and keeping it clean seems superior to the CB-6000. In my opinion, grinding and polishing are necessary for long-term wear. I started by cleaning all interior surfaces with a Dremel grinder, then rounded and smoothed various edges on both inside and outside (a lesson learned later when skin got caught during morning erections). Most edges began as sharp and rough, which isn’t ideal next to your privates over extended periods. After the heavy grinding was done and I carefully checked for burrs (causing a few uncomfortable mornings because I hadn’t looked closely enough), I smoothed and polished until everything felt universally smooth and looked shiny. Note: Reaching the inner cage can be tricky, and while I didn’t achieve a mirror finish inside, perhaps with more time or better tools it could be done. Anti-Pullout Addition: With the cage finished, fitting a spare KSD anti-pull-out device was fairly easy. Just drill two holes in the plastic to let the permanently mounted pins on the cage pass through, reshape via sanding/light grinding and heat for a smooth fit inside the tube, and it’s ready. I realized too late that I should have kept this larger than the unit used in my CB-6000 (which served as my guide). The Bon4M isn’t oval, and its tube diameter is up to 5mm taller, so I need to reorder from K4H with a bit more size for added security. Currently, it’s hard to pull out during showers but not impossible—a reasonably easy fix. The Ring: I usually use the 48mm ring on my CB6000 but wanted to tighten things up (metal adds weight), so I dropped down to the 44 mm size (one of four rings included, this is second smallest). I prefer the rectangular Bon4M ring design over round ones (like my MM) because rectangles don’t dig into me as much. Like the cage, the interior surfaces need attention. It’s hinged and requires smoothing, cleaning, and rounding all edges across the whole ring. Grind smooth, round every edge you find, polish until mirror-shiny, and it’s good to go. The spacing on the Bon4M is fixed at what I measured as 18mm (ring to device). This was too much for me; one testicle slips out when hot, sweaty, and active (you learn surprising things about yourself over time). I need between 11-14mm, which took some effort. Rather than mess with the fixed pins in the cage, I chose to drill out the two female holes in the ring itself. This process was a hassle—I likely went through 8-10 bits drilling deeper into the stainless rings by 3-5mm. The pins are graduated, and I decided to just drill for the larger diameter hole, being careful not to go all the way through. Adding that 3-5mm of depth lets me set the cage/ring distance with a spacer (which they don’t include). I used spacers from my various CB series models and ground one down until it hit the desired depth. The device stays rigid when assembled—just ensure you don’t drill the ring guide holes too large, as those provide rigidity. Pin: Since the Bon4M isn’t designed for spacing adjustment, there is only one stainless pin (though they include a second) which is standard round rather than oval like the CB6000. The pin has a hole where the lock goes (a basic lock is included). Because I wanted adjustable spacing, I added a second spacer behind the lock once the depth was set correctly; this maintains rigidity. It’s not super elegant and adds another small piece to track, but it works for now. The post also extended beyond the lock by 3/8”, which isn’t ideal for concealment, so I ground that down and polished it up. Overall, security is much better than with the CB6000—I know I can’t just break off the pins if I need to escape. That said, I’d argue the pin and locking mechanism remain the weakest part of an otherwise elegant package. The lock pops out easily or can be cut off and sits well away from the rest of the device. Something to consider for later. HOW DOES IT WEAR I’ve been in a “fiddle” / “wear” / “fiddle” cycle for about 10 days. My wife told me I need to hand over the key tonight, so it looks like I’m stuck with my modifications for a while. I had to switch from the smaller ring to the 47mm one (similar to CB). Nights were impossible before this change; that pain just wasn’t good enough. Beyond that issue, I really enjoy the Bon4M after all the mods. It’s far superior (for my anatomy and goals) than any other ball-trap device I’ve owned for long-term wear. It fits nicely, isn’t too heavy, and is easier to put on/take off compared to the CB6000. The hinged ring isn’t perfect but with my work done, it proves very comfortable without needing extra covering over it. Pull-out resistance is similar to the CB-6000 but can be improved with a revised KSD design (which I’ll do; they might even make one if sales increase). I like the look—especially after polishing—and knowing it’s metal makes a difference; this won’t come off without either a key or a Dremel. It is slightly less concealable than the CB6000.

they’re quite alike. The hygiene aspect is much improved, and so far I’d rate it highly for both comfort during wear and security. Apologies if this post runs long; some of you might still be on the hunt for that ideal device and have considered the Bon4M as a possibility. Hopefully my review offers some value. I plan to return in a few weeks with an update on how things are progressing.