1. Pull the gripper hole over the knob end of the P-tainer, dots facing out.
2. Flip the gripper up out of the way.
3. Set the dome end of the P-tainer over your glans.
4. Hold the P-tainer against your glans by the knob end with your non-dominant hand.
5. With your dominant hand, wrap your thumb and index finger around the bottom of your shaft and pull up on the skin while pushing the P-tainer into your body, rolling whatever slack skin you have up onto the body of the P-tainer.
6. Use your other fingers on the hand holding the knob to flip the gripper down over your skin.
7. Pinch the outside of the silicone to smooth out any wrinkles. The skin should sit flat, with the tip near the circle at the top of the gripper.

Full walkthrough with pictures and video: How to Wear Your P-tainer.

Give each one a real wear — long enough to sit, walk around and forget about it. You are looking for the one that holds without pinching and stays put without you thinking about it. One a day is a good pace; back to back in the same hour is not a fair comparison.

• Feels tight around the body, or leaves a mark? Try the next size down.
• Skin will not stay rolled up, or it works loose? Try the next size up.
• Two neighbours both feel close? Go with the smaller one. Skin settles and the fit loosens slightly over the first few wears.

Sizes in this kit step in 2 — 8, 10, 12, 14, 16 — which is our full diameter range, so whichever one wins is a size you can order for real.

The string has a pre-tied loop at each end. Loop one end around the knob end of the P-tainer and the other around the neck of the water bottle.

Fill the bottle part way and add water until the tension feels pleasant — around 8oz, roughly half a bottle, is a reasonable place to start (100% full is about 17.5oz). One ounce of water is almost exactly one ounce of weight, so the bottle doubles as a rough scale.

When you want the exact number, hang the bottle from the tension gauge. It reads to 500g / 20oz. Our weights come in 4oz increments, so that is a useful step to aim for once you know what you like.

Tie your own loops: the string comes with loops already tied, but knots in this cord work loose over time. Tie each end yourself with an adjustable grip hitch, at the length that suits you. It grips under tension, slides when you want to change the length, and won't shake itself undone.

Each P-tainer in this kit comes with a stiff gripper in its matching size, so you are always comparing like with like. If you swap P-tainers, swap to the gripper that matches it.

You can also mix and match. The grippers are not locked to one P-tainer — try a gripper a size up or down from the P-tainer you are wearing to customise how tightly it holds. A smaller gripper grips harder, a larger one sits gentler, so you can fine tune the fit well beyond the five sizes in the box.

The gripper should hold your skin flat against the body of the P-tainer without digging in. If it rolls or bunches, take it off and re-seat it rather than pulling it tighter.

The stiff silicone in this kit is only slightly stretchy, which is why it holds firmly and why it sizes to match your P-tainer. Our soft silicone is very stretchy — more comfortable for all-day wear, but you generally want it one size below your P-tainer. Both are on the Silicone Grippers page.

Every piece in this kit is the standard +0mm length, which is what most people wear. This kit is about finding your diameter.

If you have a lot of coverage and none of the five feels like it is holding enough skin, length is probably the missing variable. The Demo Pack - Extended P-tainer sends six lengths in the size you choose, or take the P-tainer Length Quiz to see where you land.

Nothing should ever hurt, go numb, or change colour. If it does, take it off and give yourself a break. Remember these are demo pieces: hand wash only, keep them out of hot cars, and treat them as a sizing tool rather than a long term device.

If something does not feel right or you cannot get it to work, get in touch — we would rather hear from you early.