STEIN ASCENTRA Knee Ascent System - SRS Knee Ascender Kit for UK Arborists

The STEIN ASCENTRA Knee Ascent System is an upgraded knee ascender kit designed for UK arborists running Stationary Rope Systems (SRS/SRT), working in conjunction with a foot ascender to capture the progress made with each step and convert it into efficient upward movement. The ASCENTRA uses a STEIN Chest Ascender Rope Clamp (SS-4922978088) on a 4mm HMPE cord lower sling with a 24-strand protective outer sheath, paired with high-response bungee cord for immediate action during movement. Two colour-coded STEIN CONNEXT karabiners (Blue and Gold) are included for fast, identifiable connection during setup. Compatible with ropes from 9mm to 13mm, the system can be attached to a chest harness or directly to a tree climbing harness. Available from Gustharts with UK stock ready to ship.

STEIN is a British arborist and forestry equipment manufacturer that develops field-tested products specifically for professional tree care, operating as part of the Fletcher Stewart Group — one of the UK's principal arborist product distributors.

⚠ The STEIN CAMBO Foot Loop is required to complete this system and is not included in this kit. It is available separately in three sizes — Small, Medium and Large — matched to your footwear size. See the Pairs Well With section below. Select the correct size before purchasing.

⚠ This product is not PPE. It is a climbing aid for progression only and must never be used for life safety or fall arrest. Maximum load: 120kg. Professional instruction from a fully qualified and competent trainer is strongly recommended before use.

Key Features

• Designed specifically for SRS/SRT climbing systems — captures upward progress made by each foot ascender step for efficient, smooth ascent
• STEIN Chest Ascender Rope Clamp (SS-4922978088) — dedicated rope clamp for reliable rope progression
• 4mm HMPE cord lower sling (SS-5530027P01) — high-modulus polyethylene construction with 24-strand protective outer sheath for durability and abrasion resistance
• High-response bungee cord — provides immediate, fast action during movement for smooth climbing rhythm
• STEIN CONNEXT karabiners in Blue and Gold — colour-coded for quick identification during setup and reconfiguration in the canopy
• Compatible with ropes 9mm to 13mm — covers the full range of arborist climbing lines in common SRS use
• Attaches to chest harness or tree climbing harness — flexible attachment options to suit different harness configurations
• Easy to install and remove — quick to clip in and out of your climbing system
• Self-assembly kit — supplied as components for user assembly; allows configuration to suit individual body size, harness setup and climbing technique
• Maximum load 120kg — do not exceed this limit under any circumstances

What's in the Kit

Technical Specification

ASCENTRA vs the Original STEIN Knee Ascent System

The ASCENTRA is an updated design from the original STEIN Knee Ascent System. If you're familiar with the original or are considering upgrading, here's what's changed:

The most practical upgrade in the ASCENTRA is the colour-coded CONNEXT karabiners. During self-assembly and mid-climb reconfiguration, having Blue and Gold karabiners in clearly designated positions reduces setup errors in the canopy. The updated sling construction and dedicated SRS focus also reflect the continued shift in professional UK arboriculture toward SRS climbing as the primary technique. See the full STEIN climbing range here.

Important Use Guidance

This product is not PPE and is not a life-safety device. The STEIN ASCENTRA is a climbing aid designed to improve ascending efficiency only. It must never be used for fall arrest, life support or any purpose other than progression assistance within a correctly configured SRS climbing system.

Maximum load is 120kg. Do not exceed this limit. This includes the climber's body weight plus all carried equipment, tools and clothing.

The STEIN CAMBO Foot Loop is not included and is required. The ASCENTRA cannot be used as a complete system without a CAMBO Foot Loop. Purchase the correct size for your footwear before assembling the system — see the Pairs Well With section below.

This is a self-assembly kit. Because every climber's body size, harness setup and climbing technique differs, the ASCENTRA is supplied as components for user assembly. Professional instruction from a fully qualified and competent trainer is strongly recommended before use. If you are unable to take responsibility for correct assembly, do not use this product.

Inspect before every use. Check all components — ascender, sling, karabiners and bungee cord — for wear, damage or deformation before each session. Remove any damaged component from service immediately.

Ensure system compatibility. Confirm all components in your climbing system are compatible with each other and with this product before use.

Also Known As

The STEIN ASCENTRA is also referred to as a knee ascender, knee cam, knee progression system, knee ascent aid and SRS knee system. It is sometimes described as a knee roller or knee ascent kit in arborist discussions. For ordering, reference STEIN ASCENTRA Knee Ascent System. The separately required foot loop is the STEIN CAMBO SRT Foot Loop, available in Small, Medium and Large.

Pairs Well With

The STEIN CAMBO Foot Loop is required to complete this system — it is not included in the ASCENTRA kit. Select the correct size for your footwear:

• STEIN CAMBO Foot Loop — Small (SS-55 310 27 030) — for climbing boots up to EU size 43
• STEIN CAMBO Foot Loop — Medium (SS-55 310 27 040) — for chainsaw boots EU sizes 41 to 44
• STEIN CAMBO Foot Loop — Large (SS-55 310 27 050) — for chainsaw boots EU sizes 45 to 46

Sizes are for guidance only and may vary between footwear brands. If you are between sizes, size up.

• Foot Ascenders — the ASCENTRA works in conjunction with a compatible foot ascender; ensure your foot ascender is compatible with your rope diameter and climbing system
• Climbing Harnesses — the ASCENTRA attaches to a chest harness or directly to your tree climbing harness
• STEIN Climbing Equipment — explore the full STEIN SRS climbing range

Explore More

• Climbing Equipment
• Climbing Harnesses
• Work Positioning Lanyards & Accessories

FAQs

What is the STEIN ASCENTRA used for?

The ASCENTRA is a knee ascent system for SRS/SRT climbing. It works alongside a foot ascender to capture upward progress with each step, making ascent smoother and less physically demanding. It is a climbing aid for progression only — not PPE.

Is the STEIN CAMBO Foot Loop included?

No. The CAMBO Foot Loop is required to complete the system but is not included in the ASCENTRA kit. It is sold separately in Small (up to EU 43), Medium (EU 41-44) and Large (EU 45-46) to match your footwear size.

Is the ASCENTRA PPE?

No. The ASCENTRA is a climbing aid for progression assistance only and must never be used for life safety, fall arrest or any purpose other than its intended function within a correctly configured SRS system.

What is the maximum load for the ASCENTRA?

120kg. This includes the climber's body weight plus all carried tools, equipment and clothing. Do not exceed this limit.

What ropes is the ASCENTRA compatible with?

The ASCENTRA is compatible with ropes from 9mm to 13mm, covering the full range of arborist climbing lines in common SRS use.

Why does the ASCENTRA come as a self-assembly kit?

Because climber body size, harness configuration and climbing technique all affect how the system should be set up. A pre-assembled configuration cannot suit every user. STEIN strongly recommends professional instruction from a fully qualified trainer before assembling and using the system.

What is the difference between the ASCENTRA and the original STEIN Knee Ascent System?

The ASCENTRA uses an updated ascender, a new 4mm HMPE lower sling with a 24-strand cover, and colour-coded STEIN CONNEXT karabiners (Blue and Gold) replacing the original matched karabiners. It is specifically designed for SRS with an explicit 120kg maximum load rating. See the comparison table above for full details.

Can the ASCENTRA be used in DRT/MRS systems?

The ASCENTRA is designed primarily for SRS/SRT. If you run DRT, the original STEIN Knee Ascent System was specified for both DRT and SRT. Confirm compatibility with your specific system setup before use.

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