Number One STP

by Number One Laboratories


The Number One STP is Number One Laboratories' original STP model.

Those familiar with Transthetic's EZP will recognize the style and shape of this STP packer, though this model comes at a 3rd of the price. Compared to the EZP, the Number One STP has a narrower bowl but a wider hole in the shaft. This wider hole allows for use without restricting your stream. The lower price tag makes this a great STP for beginners. 

Check out Alexander Erin's Review:



Number One Laboratory* STPs are made from Platinum Silicone with a soft powder finish. Every model sold is completely handmade using the best materials available and thoroughly checked for quality and durability. 

- Length: 6.25 inches 
- Cup Length: 3.25 inches 
- STP Height: 2.25"
- Cup Width: 1.5 inches 
- Shaft Circumference: 3.5 inches 

Platinum silicone may be cleaned using any one of the following methods:
- Hot water and soap
- Diluted bleach
- Overnight denture cleaning tablets
- Boil for 3-5 minutes

The Slingshot Harness is a harness made to pair with this STP. 

If you are not a person of color, we strongly encourage you to buy the "light" tone. Historically, white folks have generally been unhappy with the "medium" shade, which is similar in color to a light brown M&M. 


*First-time users, we strongly recommend that you practice in the shower before attempting to use it in public. Even if you have had success with other STPs in the past, every STP is different and requires some getting used to. 

*Please note that due to the sensitive nature of this product, all sales are final. 

*This company used to be called Form Function 

Customer Reviews

Based on 4 reviews
Charles Stoers

Number One STP

Mac Martinez
Thanks again!

This is my 2nd purchase! I would love if it was an inch longer to clear better... but love this.

Functional and sturdy

This is my first STP purchase. The bowl was a bit more narrow than I expected and I couldn't figure out a way to comfortably pack with it. I bought the slingshot harness, but didn't realize the harness wasn't compatible with this STP in particular. I successfully used it in the shower and at the toilet, but I was too scared to try using it while wearing clothes. If I wasn't careful with releasing my stream, the bowl would tend to overflow and leak from the back. It could be poor positioning on my part, but I haven't figured out how to position it in a way that wouldn't leak onto my underwear. Overall a good first STP, although I wish the price was a bit lower, can't complain too much compared to the price of other STPs out there.

Alexander Farley
Stand to Pee on self if not careful

I do love STPs as a Trans person. This one however struggles with leaks. If you aren't pressing it firmly to yourself you WILL leak out the back and pee yourself which can be quite humiliating in public settings. As long as you're being diligent though, it aims well and sometimes I can pass in a men's restroom.


You can expect your order to ship within 2-3 business days after purchase. Print to order items, such as t-shirts, will sometimes take longer and will ship separately.

Final Sales

Please note that due to the sensitive nature of the items in question, all STP, Packer, Harness, and Underwear sales are final. Please make sure you have double-checked product size guides and have selected the correct item.

International Orders

Please note that for all non-US orders, you may be charged local taxes in order to retrieve your order. See our Shipping Policies for more details.