Compact Sport STP 4": Low-Bulk Stand-to-Pee Packer by Number One Laboratory

The Model D's shaft and head, in the slimmest profile Number One Laboratory makes.

The Compact Sport STP is Number One Laboratory's low-bulk version of their Model D. Same shaft, same head, but with smaller balls, a shorter cup, and a lot less bulk. If the standard Number One STP feels too big for your frame or your pants, the Sport keeps the parts that matter and cuts the rest.

Here's the tradeoff, up front: the shorter receptacle cup needs more precise placement than a deeper-cupped STP. You'll want to ease up on your stream more than you would with a standard model, and it may take a little longer to learn. Also, because the cup is so compact, it works best in tighter underwear or a harness that holds it firmly against your body. Loose clothes will shift it and make leaks more likely.

It's made from 100% body-safe platinum silicone with a soft powder finish. The matte outside cuts down on chafing and gets rid of that tacky silicone feel. Each one is handmade by Number One Laboratory, then finished and checked by hand.

💪 Bulge Rating: 3 / 5

A moderate, natural-looking bulge. It's smaller than the standard Number One STP thanks to the smaller balls. Use the TGS Bulge Rating Guide to compare every STP in the lineup.

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📐 Product Details

Brand: Number One Laboratory, maker of handmade STPs for the trans community
Material: 100% Body-Safe Platinum Silicone with soft powder finish

• Shaft Length: 4 inches / 10.1 cm
• Width: 1.25 inches / 3.2 cm
• Height (base of balls to top of shaft): 3.5 inches / 8.9 cm
• Same shaft and head as the Number One Model D, with a compact cup and smaller balls
• Reduced bulk profile: made for tighter pants, active wear, and smaller frames
• Shorter receptacle cup: needs more precise placement than deeper-cupped STPs
• Soft powder matte finish: less chafing, no tacky silicone feel
• Completely handmade: each one finished and quality-checked
• Boilable and dishwasher safe (top rack) for full sterilization

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🩲 Best Pairings

Because the Sport's compact cup needs to stay firmly in position to work well, a snug harness or fitted STP underwear is especially important with this model:

• Slingshot Harness: Number One Laboratory's own thigh harness, made for their STP line, including the Sport
• Cake Bandit Harness: holds it in place under any underwear
• STP Briefs, STP Boxer Briefs, or STP Jock: a working fly and inside sleeve keep it in the same spot

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🧼 Care & Cleaning

Platinum silicone is non-porous and easy to fully sterilize. Clean using any of the following:

• Hot water and soap: your everyday clean after use
• TGS Packer & Toy Cleaner: fast and gentle, and it conditions the silicone
• Boil for 3–5 minutes: full sterilization
• Top rack dishwasher: no detergent needed

Air-dry completely before storing. For long-term storage, dust lightly with Packer Renewing Powder to maintain the soft powder surface. Store in a cool, dry place out of direct sunlight.

Water-based lube only. Do not use silicone-based lube. It breaks down platinum silicone over time.

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🚿 First-Time Use Tips

The Sport's compact cup takes more patience to learn than deeper-cupped STPs. Cup placement matters more here. Give yourself extra practice sessions before using it in public, and expect it to take a bit longer to get used to than a standard model.

1. Shower, water off: practice the seal with no clothes on. With the smaller cup, focus on getting a flush, centered seal before you start to go
2. Toilet, no clothing: practice with a moderate stream. The Sport works best when you're not at full flow pressure
3. Underwear on: the Slingshot Harness or snug Cake Bandit STP underwear holds the Sport in the same spot. Loose clothes will shift it
4. Fully dressed: once you're getting it clean every time at home with clothes on, you're ready for public use

For the full technique guide, read our Complete STP Guide.

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❓ FAQ

Who is the Sport designed for?
Anyone who wants the Model D's shaft and head with less bulk. It's great if you wear tighter pants, want a smaller bulge, or find a standard STP uncomfortable. Because of the smaller cup, it's better for experienced STP users than total beginners.

Is this good for beginners?
It can work as a first STP, but the shorter cup needs more precise placement than deeper-cupped models. If you're completely new to STPs, the STP Freely or Packer Gear STP are more forgiving places to start. The Sport pays off once you have the technique down.

How does this compare to the Model E?
The Model E is smaller overall, with a 3-inch shaft versus the Sport's 4-inch. The Sport has more shaft length and is closer to a standard STP in terms of function, just with less bulk around the cup and balls.

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📦 Shipping & Returns

Orders typically ship within 1–3 business days in plain, unmarked packaging from our shipping dept. No logos, no product names, nothing that gives away what's inside. Learn more about our discreet shipping promise.

All sales of STPs, packers, harnesses, pleasure toys, swimwear, and underwear are final due to legal restrictions. See our full Returns & Refund Policy.

All international orders are final sale. Local taxes, duties, and customs fees are the customer's responsibility. See Shipping Policies.