No. The Z-RAM steel replacement barrel asked about is for the Umarex HDR68/TR68, not the HDB68/TB68. Z-RAM's model-specific answer and the current HDR68/TR68 barrel listings agree on that scope. Sharing .68 caliber does not make these different platforms use the same replacement barrel.
The model letters carry information that the caliber does not
HDR68 and TR68 are regional names for the same revolver family. HDB68 and TB68 identify a different platform. In both pairs, the regional name changes; it does not turn HDR into HDB. Keeping the full model name is more useful here than searching for “Umarex .68 barrel.”
Caliber identifies a projectile-size family. It does not specify the replacement barrel's whole shape, mounting arrangement or relationship to the marker's mechanism. A product must identify the intended platform as well as the caliber. The HDB68 name cannot be added to an HDR68 compatibility list just because both end in 68.
The two HDR68 barrel offers stay within the same family
The HDR68/TR68 steel-barrel package with an extension lists one threaded barrel, one 10 cm extension and one thread protector. The separate steel-barrel offer lists one threaded barrel, one thread cover and one reinforced spring.
That package difference helps an HDR68/TR68 owner distinguish the offers. It does not make one of them an HDB68 version. Both cards below remain HDR68/TR68 comparisons; neither is a recommended substitute for an HDB68/TB68 barrel.
A front extension is not the replacement barrel
A product described as a screw-on barrel extension is a different component from a replacement barrel. Even if a front attachment is listed for HDB68, that does not establish that the separate HDR68 replacement barrel fits that marker.
If your marker is an HDB68/TB68, keep that full identity—and its generation where specified—attached to the part you are checking. The questioned replacement barrel is listed for HDR68/TR68, not HDB68/TB68.
Two HDR68/TR68 offers—not HDB68 replacements

Tuning Barrel for Umarex T4e HDR68 TR68 STEEL with Extension (with thread) | 40j+
HDR68/TR68 threaded steel barrel with a 10 cm extension and thread protector. Shown to identify the questioned package, not as an HDB68/TB68 option.
View HDR68 package scope
Tuning Barrel T4e HDR68 TR68 STEEL with thread
Separate HDR68/TR68 steel-barrel offer with thread cover and reinforced spring. Different package contents do not change its listed model family.
Compare HDR68 barrel contentsGeneral Z-RAM viewing: model families
This Z-RAM introduction lists the HDR and HDB families separately among the shop’s model groups. It supports general model-name orientation; the exact replacement-barrel boundary is explained above.
▶ Play on YouTubeFind the Best Umarex T4E Parts at Z-Ram.net . HDR68 TR50 HDP50 TS68 Pepperball First Strike
Channel: Z-RAM
General Z-RAM viewing: product categories
The category tour introduces parts such as barrels alongside other Z-RAM products. It is optional shop orientation, not evidence that a replacement barrel and a front extension are interchangeable.
▶ Play on YouTubeThe Ultimate Shop for RAM Tuning Parts: Ammo, Valves, Chambers, and More HDR50 TR68 FSC TCP
Channel: Z-RAM
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Laws and regulations governing the purchase, possession, installation, modification, and use of the products described on this page vary by country, state, and local jurisdiction and may change. Before purchasing, installing, modifying, or using any product, you are responsible for confirming that it is permitted in your location and for your intended purpose. Product availability or delivery does not mean that purchase, possession, installation, modification, or use is lawful in your jurisdiction. Z-RAM does not provide legal advice, and the information on this page must not be treated as legal advice. If you are unsure, contact the competent local authority or a qualified legal professional.
