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Head·Ski boots·Accessories Ski Boots

Head Power Strap Sidas P4 40 mm

Stiff power strap that sharpens power transfer between shin and boot for a direct, precise feel.

91 €
1Size
91 €
  • Delivery in 2–5 business days
  • 30-day returns
Ski expert
Not sure about the size? Chat with a ski expert, or call +46 370 33 97 70.
P4
Stiffest
P4 is the stiffest variant, used by World Cup-level skiers.
Metal
Buckle
Metal buckle allows precise, secure tightening of the strap.
Direct power
Response
Delivers better response, stability and comfort in aggressive skiing.

About Head Power Strap Sidas P4 40 mm – Accessories Ski Boots

The Head Power Strap Sidas P4 is a powerful and stiff power strap that provides maximum control and precision in your skiing. It is designed to improve the flex of your ski boots and create a more direct power transfer between your shin and boot. The result is better response, higher stability, and increased comfort, especially during aggressive skiing.

The P4 is the stiffest version in the series and is used by many World Cup level skiers, including the entire Head team. It is similar to the Booster strap but is even harder and more direct in feel. The strap is equipped with a metal buckle that makes it easy to tighten precisely and securely, while the reinforced construction protects against edge impacts.

This is the choice for the advanced skier who wants a firm and controlled skiing feel with professional performance.

Head Power Strap Sidas P4, Specifications

  • Model: P4 (the stiffest version)
  • Improves flex and control
  • Metal buckle
  • High performance
  • Ideal for experienced skiers

Fit & last

The last is the boot’s width across the ball of the foot. 100 mm is a medium width and suits most people. If you have a wide foot or high arches, we can spot-heat the shell in the store where it presses. The boot should feel snug when you try it on: your toes touch the front when you stand straight and pull back when you bend your knees. The liner packs out 3–5 mm during the first week, so a boot that feels comfortable in the store will be too big after a week. Always measure mondopoint — boot size has nothing to do with your normal shoe size.

Boot fitting

Buy your ski boots from us and you get free boot fitting for 1 year from purchase. That means we heat-mould the liner and grind or punch the shell at no extra charge. If we need to add materials or products, such as a custom-moulded footbed, you only pay for those — not for the work. You’re welcome to drop into our store at Isaberg, Sweden for up to 1 year after your order is placed.

Shipping & returns

Delivery time: 2–5 business days to Germany, from our warehouse in Hestra, Sweden. If the boot doesn’t fit right, free boot fitting is included for 1 year from purchase. Call +46 370 33 97 70 if you’re unsure before you order.

Head Power Strap Sidas P4 40 mm specifications

CategoryAccessories Ski Boots
ModelP4 (stiffest variant)
BuckleMetal buckle
Width40 mm
LevelAdvanced skiers
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Choosing ski boots
Your ski boots affect your skiing more than any other piece of equipment — and they’re the hardest to choose online. Below we go through mondopoint, flex, last and what a boot fitting does.
Mondopoint — measure your foot, not your shoe size
Ski boots are sized in mondopoint, which is the length of your foot in centimetres. Stand with your heel against a wall, mark your longest toe and measure. That measurement is your size. Your EU shoe size is a poor starting point because it varies between manufacturers. A ski boot should feel snug when it’s new — the liner packs out 3–5 mm during the first week of skiing.
Flex and what the number means
Flex describes how much force it takes to bend the boot forward. 60–90 is soft and forgiving, 90–110 is an all-round level, 110–130 is stiff for skiers who ski hard, and above 130 is race level. The number isn’t standardised between manufacturers, so a 100 from one brand can feel like a 110 from another. If you’re heavy or ski aggressively, you want a stiffer boot; if you’re lighter or a beginner, you want a softer one.
Last — the width of your foot
The last is the boot’s width across the ball of the foot. Narrow is around 98 mm, medium around 100 mm and wide around 102 mm. A medium last suits most people. If you have a wide foot, a last that’s too narrow isn’t something you get used to — but the shell can be heat-moulded to make room where it’s needed.
Boot fitting makes the difference
Nine out of ten skiers have something adjusted at their first fitting. We analyse your foot, heat-mould the liner and grind or punch the shell where it pinches. A custom-moulded footbed gives better heel hold and less foot fatigue, and is the single biggest improvement you can make without changing boots. Buy your ski boots from us and free boot fitting is included (materials such as footbeds are paid separately), and you’re welcome to drop into the store for up to 1 year after your order is placed.
Socks and fit go together
A thin, knee-high ski sock with no seams across the ball of the foot is the right choice. Thick socks make the boot tighter without making it warmer — it’s the air inside the boot that insulates, and a boot that pinches gives you cold toes. Never wear two pairs.
Frequently asked questions
Ski boots are measured in mondopoint, which is the length of your foot in centimetres. Put your heel against a wall, measure to your longest toe and choose that size. The boot should feel snug when it’s new.
Ski expert
Didn’t find your answer? Call +46 370 33 97 70 or chat with a ski expert.
Head Power Strap Sidas P4 40 mm
Select size
91 €